If you're just here for the sexy part, please proceed to the next chapter.
It wasn't as though Barbara meant to keep falling in love with trolls.
Blinkous Galadrigal was intelligent and charming and enthusiastic about everything. He and Barbara could, and did, talk for hours. It had started out, as so many things in Barbara's life did at the time, as being all about her son Jim, but then they began discussing literature and music and everything expanded from there.
AAARRRGGHH was brave and kind and a wonderful listener and deeply caring and so very gentle. He was amazingly expressive, and showed more cleverness that some people realized in his brief but well-timed comments.
And, unlike her with previous troll suitor – she still didn't remember what exactly had happened with Walter Strickler but she knew he'd hurt her and Jim – Barbara's son trusted Blinky and AAARRRGGHH implicitly.
She couldn't quite accept what she'd been told, that she'd continued a relationship with Walter after Jim told her the man made him uncomfortable. She could understand her past self might want something just for herself, something outside of being Jim's mother, or think that her son was simply uncomfortable with the idea of his mother dating anyone, but she couldn't believe that her past self would seriously consider a relationship with anyone who made her child feel unsafe.
Jim became evasive when she said that, so he probably hadn't said it so explicitly the first time, and Barbara didn't want to doubt him now that he was finally sharing what was going on in his life, so she dropped the subject and simply reminded Jim that he deserved to feel safe, especially in his own home, and that he could tell her anything.
When he'd re-introduced her to 'Mr Blinky', they'd quickly renewed the friendship she couldn't remember, and when Barbara met AAARRRGGHH, he had been easy to befriend as well.
The fact that they both liked her cooking certainly hadn't hurt.
Their relationships had been far more slowly built.
She hadn't been entirely certain if Blinky was flirting with her or not, the first few times it happened. It could've been a cultural difference, or he could've misconstrued how human interactions worked since his primary observations were of Jim, Toby and Claire. When she saw him behave similarly towards AAARRRGGHH, she concluded it was just how Blinky was, and pushed down the disappointment this thought prompted.
When she learned Blinky and AAARRRGGHH were romantically involved with each other, Barbara smiled for them – they were well-matched – but wondered and worried about Blinky's continued flirting.
After what had happened with her first husband …
Finally she sat Blinky down and, over tea and whipped cream, outright asked him. He admitted he'd been flirting with her, and apologized if he'd made her uncomfortable, and assured her that AAARRRGGHH was aware of and okay with it. "Though of course if you aren't alright with it, I will stop immediately."
Barbara appreciated the honesty but hadn't been sure how she felt about it, so she ended up talking it over with AAARRRGGHH. The massive troll quietly encouraged her to air all her worries and offered what reassurance he could.
Yes, he'd known Blinky was flirting with Barbara. No, he didn't mind; he liked Barbara too, though not that way, but maybe he would eventually. (From what he'd managed to explain, Barbara thought AAARRRGGHH might be demiromantic, and so didn't develop that sort of attraction until he was already close to someone.) Yes, AAARRRGGHH and Blinky had been together for a very long time. No, they'd never involved a third party in their relationship before, but AAARRRGGHH and Blinky thought they could make it work if Barbara were interested in trying. No, there was no rush, Barbara could take all the time she needed to sort out her feelings; troll often took years or even decades to decide on their relationships.
So, over the next year, Barbara had tentatively grown closer to Blinky, and to AAARRRGGHH.
She hadn't expected to fall in love with either of them, but she fell in love with both.
Barbara and Blinky had started dating two years after they'd met. Barbara and AAARRRGGHH took a bit longer to work out exactly what they were to one another, whether they wanted to date each other or were simply friends bound by their mutual love for Blinky, but after five years of knowing each other, they decided they were dating as well.
Jim fainted when they told him. When he woke up and confirmed it had not been a crazy dream, he declared that he never wanted to know any further details.
To be clear, I do ship Stricklake (and think it will happen in the show because I feel he's been set up for a redemption arc, and villains who are set up for redemption arcs and have love interests usually end up together with said love interests), but this story takes an anti-Stricklake view because it is just as believable for Barbara not to want him back. An OT4 I have seen proposed is Blarrrgharalt (Blinky, AAARRRGGHH, Barbara, and Walt) which ... could potentially also work, but I already had this story written as-is.
