MORVEN CHRISTIE is a warrior: fearless, unapologetic and strong. It's a Thursday morning and over the next hour we will run the gamut from misogyny and the darker side of social media to why she no longer cares a jot what anyone thinks about her.

The Glasgow-born actor, who returns to our screens in BBC drama The A Word this week, doesn't do trite. She is forthright and candid, yet exudes a warmth that negates any jagged edges. Christie feels things deeply. Sometimes a little too much.

We're here to talk about her role as Alison Hughes, a woman whose young son Joe (Max Vento) has been newly diagnosed with autism. The opening series of The A Word dealt with the fallout as Alison and her husband Paul (Lee Ingleby) struggled to get their heads around the juggernaut news.

"Series one, certainly from my character's point of view, was a lot to do with denial," says Christie. "Dealing with the shock and aftermath of a diagnosis and not really understanding what it means, wanting to accept it or reach out for help.

"If anything, series two is the opposite of that for Alison. She has fully embraced what it means and is open to discovering how her son's needs change and, in turn, their family's needs change."

Christie, whose past roles include Grantchester and The Replacement, isn't the sort to simply learn her lines and show up. Immersive is the word that the 36-year-old actor uses and we're talking both-feet-in, no-holds-barred absorption.

Alison with her often abrasive manner and lack of social niceties is glorious antithesis to the central casting, picture-perfect TV mum. "I kind of admire that," says Christie. "I feel like she woke up those traits in me a wee bit. She doesn't apologise for herself.

"I admire that steel in her. It is definitely a female thing, isn't it? This need to be nice, pleasing, quiet, liked, visually pleasing and all of that. But it is a construction. It is not necessary and it is a madness, really. It is such a waste of time and energy – and so exhausting.

"Actually, when you remove that element of worrying what people are thinking about you – and how to behave in order to make them think the right thing about you – it is incredibly liberating. You just have so much more time to spend on other stuff."

It sounds like Christie has had an epiphany. "Definitely," she says. "And I do think playing Alison was part of it, the reaction to her. When you are playing a character, you are not sitting outside of them and judging their behaviours. You are walking in their shoes.

"I was like: 'OK, she doesn't apologise for herself' and 'yeah, she can be quite bullish'. But Alison has just been given information that she doesn't know how to cope with and it is overwhelming. I had a lot of empathy for her."

Not everyone felt the same. While The A Word garnered widespread acclaim for its powerful subject matter, Alison as a character polarised many viewers. Some found her fierce, no-nonsense demeanour refreshing, yet others dubbed her "self-absorbed", "cold" and "unaccepting".

There were worse terms used. "There was this whole reaction to her as a 'terrible mother', 'bitch' and 'awful woman'. I thought: 'Wow! Walk a step in her shoes …'" says Christie. "I found it shocking. Characters are very personal to me. I always feel like I'm playing them from a place inside myself."

How did that criticism affect Christie? "I took it really personally," she admits. "I felt this intense need to defend her and to defend women. I guess what that brought out in me was a quite forceful rejection of all of the nicety.

"You don't like her? Ask yourself why you feel the need to condemn this woman. What was interesting was a lot of it came from women. That I found really hard. The way we've been conditioned to judge each other. I just find it so heartbreaking and sad."

It made her realise, says Christie, how much that behaviour has become ingrained in us. "Boys are allowed to fight with each other and learn to challenge things. Girls are taught to 'be as nice as that girl' and 'be as pretty as that girl' and to constantly compare ourselves.

"I'm only realising it now, but this process has absolutely liberated me because it has enriched every single relationship in my life," she says. "You suddenly notice: 'Maybe I do sometimes compare myself to that friend …' But when I don't, I get to say: 'Aren't you a f****** badass!'

"I have watched my female friendships and work relationships blossom. I had great friendships before – it's not like I wasn't already quite a strident feminist – but it's the subtleties."

It is fascinating to hear Christie talk about this butterfly from the chrysalis metamorphosis. She has become prolific in confronting misogyny and standing up for women. Many people are afraid to put their head above the parapet. Not Christie. She will valiantly call out unjust behaviour.

"I feel very passionate about it," she asserts. "That's what has changed. It's not that those thoughts weren't there before; it's that now I won't hold them in.

"It is important that we speak up and speak up for others too. This is something you see in actors all the time, people who have got their own back but not anybody else's and it just infuriates me.

"I detest injustice. I'm done thinking: 'It's best not to say anything.' Anybody who thinks less of me for that? Good. Knock yourself out. There are fights that are worth having.

"When you stop caring so much about what people think of you, it crystallises things. You can start seeing what is right and what is wrong."

Christie is warming to her theme now as we lament the negativity within some quarters of social media. She took a break from Twitter earlier this year. "Nobody knew who the f*** I was or cared and then suddenly [after The A Word] there was this weight of opinion.

"Whether it is positive or negative, I don't want to be that engaged with people's opinions of me. I don't want to know if you think I'm wonderful or if you think I'm terrible. Either way it affects the way that I walk around the world."

The constant white noise? She nods. "It just started to feel like I had given my phone number to 10,000 strangers in a pub. I don't want to talk to 10,000 strangers by text.

"There is something about the reductiveness of 140 characters. It polarises everything. It removes nuance and context in conversation, the subtleties of thought. It makes people brash and crude. I felt it was starting to have an effect on journalism, news and politics. That is why I came off it."

Christie reluctantly reactivated her account after a three-month hiatus. "I went back on it because someone opened up an account in my name and the only way to not have that happen was to have my own blue tick [verified] account," she says.

"I guess now I don't engage in things in quite the same way, but when I do, I don't feel any sense of having to apologise for myself."

The younger of two children, Christie was born in Helensburgh and grew up in Glasgow. Her father was a drama teacher and later a lighting designer, while her mother worked in a bank then retrained as an occupational therapist.

Childhood weekends and family holidays were spent in Aviemore. "Climbing hills and skiing," she says. "I still love it up there."

It perhaps isn't a surprise that her first job was as a ski instructor. "I left school as early as I possibly could," she says. "I had been truant so much that as soon as I hit my 16th birthday they were like: 'Go if you want …' and I said: 'See you!'"

Academic life might not have been her thing, but make no mistake: Christie is a remarkably well-read and clever woman. Or as she puts it: "As much as I left school early I'm not without a brain that needs to be used."

After trying her hand at different jobs in her late teens and early twenties ("I did a bunch of stuff: taught skiing, worked in shops, waitressed and travelled a bit …") Christie began a communications course at Telford College in Edinburgh.

She soon clicked that her vocation lay elsewhere. "I got into the college, looked around and thought: 'Oh, there's actors here …'"

Christie went on to study at the Drama Centre London, although that seed had arguably been planted many years before. Her parents had met in youth theatre. Perhaps it was in her DNA?

"When I told my dad I wanted to do acting, he said: 'I wondered how long it would take you.' I had brought it up over the years and do remember him regularly telling me that '95 per cent of the profession are out of work' and all of that.

"I would go up into the loft when I was younger. I found boxes of stuff belonging to my dad from drama school filled with plays and stage makeup, that old greasepaint which has a really particular smell to it. I was like: 'Ah, I love this!'"

You get the feeling that when Christie puts her mind to something, there's little that will budge it. Yet juxtaposed with this tenacity are tantalising flashes of a far more laidback, carefree spirit.

"Once you commit to something, if it is right, then the universal momentum clicks in and all of these things happen," she says. "Doors open once you hit the right path.

"It has been like that all the way through. It's not like I haven't had difficult times. I definitely have had quite significant periods of unemployment and being unbelievably skint and in real trouble – I think I will continue to have those.

"But when you make decisions, things happen that show you those were the right ones. That is kind of what happened when I decided to be an actor."

Our paths have crossed a few times lately. Firstly when she was shooting psychological thriller The Replacement in Glasgow last year. The drama has been nominated in three categories at tomorrow's Bafta Scotland Awards, including Christie for best television actress.

More recently I visited the set when she was filming the BBC's big-budget Christmas adaptation of Agatha Christie's Ordeal by Innocence alongside Bill Nighy and Anna Chancellor. In between those two productions, Christie shot The A Word and ITV's 1950s detective series Grantchester.

To say she has been busy would be understatement. Christie is currently embracing the whole resting actor vibe. "In my head I'm chilling until Christmas." What would it take for her to give that up? She grins. "If I read something I like and want to do it."

She is enjoying keeping a low profile. "With telly I worry about people being sick of me and going: 'Oh, God, her again.' I don't want to play parts that are too much the same either."

Some actors make a career from portraying what is essentially the same character with slightly tweaked incarnations. Christie shudders at the prospect.

"I do think that happens, where you have played a part and people lack imagination, so they go: 'We have this character who has the same characteristics, let's get Morven Christie to play it …'"

"I did theatre for a long time which meant I played really quite differing roles. It is not like I went into this thinking: 'I'll just play tiny variations of myself.'"

Christie is sanguine about how her fascination with the human condition bleeds into her work. "I get really excited by other people's experiences," she says. "It is empathy, I suppose."

She has a good analogy to that effect. "I used to be a waitress in TGI Fridays for a bit and they do this really cheesy training when you start. They hit you up with all these really corny Americanisms. One of them is this thing called the 'beach ball theory'.

"You are holding a giant beach ball and from where you're standing you see it as red, but someone else will say it is blue. It is a cheesy, American, TGI Fridays thing, but it is true.

"I guess that's what I love about acting," she continues. "We are all subtly different. Even people you have huge amounts in common with, you will still have subtly different perspectives based on your experiences. It may not all be nurture either, sometimes it is just based on your spirit.

"I want to understand other people's perspectives. I want to be in them for a bit. I don't want to understand what you think. I want to understand what it feels like to be you."

Away from work what are her passions? "I swim a lot. I just started weightlifting. I spend time with my friends, go on road trips, hang out with my dog, go to the pub and eat."

Christie is a self-confessed homebody. Asked about celebrating her recent Bafta Scotland nomination, she cheerily replies: "I put on my pyjamas and watched Outlander."

Returning to Glasgow three years ago after more than a decade living in London, says Christie, has brought a renewed sense of grounding. "I have done a lot better work since I moved home and I'm happier I guess."

When we speak Christie has put her flat on the market and bought a new place. She's not leaving Glasgow, is she? "Oh no," she interjects. "I'm moving a mile down the road, if that. It is still a flat. I'm obsessed with tenements.

"My new one isn't a project, but I will do things over time just because I'm an artsy bugger and enjoy design. If I wasn't an actor that is what I would be doing."

Her mind is constantly whirring with ideas. "I want to direct," she says. "I think I might be better at directing than I am at acting. I have been writing for a while too."

What genres does she write? "Very singular POV [point of view] drama. I have a couple of ideas. There is some old source material I would really like to do adaptations of that are female-led and Scottish. There is a play about Glaswegian women that would make an amazing film, but I think it will be a tough sell."

There's a twinkle in her eye. Spill! "No, because I don't want anyone to steal it," she laughs.

"There are a couple of women – Glasgow figures – who I would love to write about and see being celebrated on screen. Someone has been trying to make a film about Jimmy Reid for a long time. I really want to see that film. In fact, I really want to be in that film."

Christie reflects that these aspirations may be longer-term. "I might be 60 when I finally do it," she muses. "With acting at the moment I feel like I don't want to reject what is coming. I still love what I do and have to make hay while the sun shines.

"The more I can juice out of this period, the more I will have to bring to the next one."

The A Word, BBC One, Tuesday, 9pm. With thanks to the Soho Hotel in London (