It didn't take long for Steve McGarrett (Alex O'Loughlin) to spring back into action after his liver transplant last season on Hawaii Five-0, but the emotional effects may be more long-lasting than the physical ones after his health scare.

Show boss Peter Lenkov told TVGuide.com ahead of Season 7 that we'll see a more contemplative McGarrett in Season 7 as he takes stock of his life. That idea is hammered home in Friday's episode, the show's 150th overall, which sees the return of the two prominent female figures in McGarrett's life: his ex-girlfriend Catherine (Michelle Borth) and his mother Doris (Christine Lahti).

TVGuide.com chatted with O'Loughlin -- who recently indicated that he plans to exit the show after Season 8 -- about what's in store for McGarrett in "Ka makuahine a me ke keikikane" ("Mother and Son").

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TVGuide.com: McGarrett and Danny (Scott Caan) have clashed a bit this season about McGarrett bouncing back too quickly from his liver transplant. Will he face any negative consequences from returning to the field so soon?
O'Loughlin:
Nah, man, he's pretty resilient, this guy, isn't he? Pretty resilient. He has a moment or two where he's like, "OK, I think it's time for me to go to bed now." He declines after-work drinks at least on one occasion and says, "I'm going to take everybody's advice and go home and watch TV because I don't feel so great." But yeah, beyond that, he's healed up good.

This season is all about a "more reflective" McGarrett after his health scare. How will we see that play out this week?
O'Loughlin:
I think the 150th [episode] is a really good example of that. It's a really important episode for McGarrett, because he gets some long-awaited closure with the two most important women in his life. ... What happens with Catherine and McGarrett in this episode, and what happens as a result of Catherine explaining, finally, everything that happened in her life that made her behave the way she did and is now going to send her off into her own trajectory that doesn't involve him, really helps humanize his mother for him. It helps humanize Doris and really helps McGarrett understand who his mother is and what her needs were, and why she did what she did. Even though he kind of knew on a head level, this stuff has really helped him feel that. And I think that's really important. He needs to move on from Catherine, which he finally now can. And, not that he's going to move on from Doris, but he can now accept Doris as Doris, without the terrible existential angst that has before now gone with it.

Will Catherine pose a problem for McGarrett and Lynn (Sarah Carter)?
O'Loughlin:
He was with Catherine for five years, six years. It was a long relationship and a really important one, and the way it ended was a great shock and was really painful. I think anyone who's had a long, intense relationship of deep love, of real, groundbreaking, life-changing love that's ended knows that you don't just get over that. And frankly, you will never, ever. It's always going to be imprinted on your DNA. That's how powerful love is, and those experiences are.

Does he still consider her the one who got away?
O'Loughlin:
No, Catherine's not the one that got away. Catherine's the one that wasn't meant to be. He understands that. He respects that. And he respects her and her choices, but I think now, knowing what he knows, there's also a sense of relief, a quiet kind of acceptance and relief, that it happened the way it did. Because imagine if they'd had kids, if they'd got married and had kids, and then she had this, like, "Oh, I've got to go and I can't tell you anything." That'd be really bad. That'd be kind of unforgivable. So at least now, the love that they had, he can hold in a sacred place that can always be nurtured. But it's not something he's going to yearn for now, because he understands it.

Frankly, the way she conducted herself wasn't great. It wasn't great. And even though he forgives her for that, that's kind of a tell-tale sign. That's more like Doris than he is comfortable with. So that doesn't take anything away from how he feels about her, but he's able to step back and go, yeah, I don't want to marry my mom.

What does McGarrett learn about Doris in this episode?
O'Loughlin:
The Wo Fat storyline seems to be something that McGarrett will never really evade. It's going to be something that's in his life on some level all the time. So, we are going to meet one of Wo Fat's relatives who's a part of this story, and the connection between McGarrett's mom and Wo Fat's father, we bring that into the light.

Hawaii Five-0 airs Fridays at 9/8c on CBS.

(Full disclosure: TVGuide.com is owned by CBS.)