Heartwarming / Parties Are for Losers

• KT comforting Yura during "Parties Are for Losers" when he opens up to her about his insecurities, especially considering she's got every reason to be a pessimist regarding her own life but still makes the most of things.
• "KT's Official Guide to Coolness" shows the events of the party and the aftermath from Katya's perspective, including how excited she is to meat and hang out with other people, her bonding with Yura and Sanya, and their decision to shelter her at Sanya's place. In particular, it reveals Yura was already aware she was a mutant and thus pf the danger in harboring her but chose to do so anyway.
• During "False Disposition", Sanya gets angry at Yura flirting with another girl and attacks some trash cans outside. Yura catches her and she's embarrassed—only for him to offer to join her and start beating them up too, with a bat like the one Sanya uses in PAFL. It's sweet in a delinquent way.
• Also in "False Disposition", Yura showing at the end that he's taken KT's advice to heart, realizing that his old defeatism was (in her words), "Really lame". Doubly so because he says it as he's heading out to become a Stalker so he can rescue her.
• It's bittersweet but in "The Mill", Sergei in a flashback gets injured while doing his Stalker work and immediately thinks about Sanya, his sister, before later being shown quitting being a Stalker. So many of his actions are motivated by protecting his sister and it shows, even if his methods understandably anger her.
• It's revealed in "Comfort Zone" that the reason Dmitry impulsively jumped in to rescue Anya from those two thugs is... he mistook her for Katya. Despite all of the awful things he was manipulated into believing of his fellow mutants, and how quickly he split ways from Katya after their escape, he still wanted to help her when it looked like she needed him.