Felix's motivations weren't exactly pure here, either.
He had family to consider. Even if this wasn't some Dyad bullshit (and he was mostly convinced that it wasn't), they were from a place that didn't prepare them for any of this, with the magic and the time traveling and the radioactive planet. It was smart to have friends now, especially ones that could help them somewhere down the line. Remus seemed flighty and nervous, a little bothered and a little desperate for someone to talk to. It made him perfect to get gossip out of and likely to know about the sorts of dark corners and hiding places they might need at some point.
It helped that he was cute, too. Felix's paranoia was hard won in these last few years, so he wasn't about to get all squishy and vulnerable right away, but Remus was nice even if he was shady.
In fact, he was a good sight after a day in the kitchens. Felix genuinely hated food service. Hated it. He'd worked at a fast food place for a week and quit the second he'd figured out that sex paid a hundred times better for half as much work. It felt like the universe catching up with him, all those burgers he'd never flipped in favor of something lucrative and illegal. They worked in shifts, thankfully no one was stuck in there for all three meals, but he couldn't wait to get out -- and Remus standing outside with a new set of shoelaces (not for him, but for Kira, who was going to need them soon) was as close to a breath of fresh air as they were going to get underground.
"You know, I did." Felix smiled, twisting the laces around his fingers before depositing them in his pocket. "Hi, pretty. You come all this way just for me?" He was always more charming around men. It was put on for sure, but not entirely disingenuous.