Okay, so I see this question pop up a lot in the threads about 'A Court of Thorns and Roses', specifically about Tamlin. People really hammer him as the sole problem, which feels too simplistic now. He's a symptom, not the cause. The entire Spring Court structure rewards his controlling behavior; it's a system built on ancient, rigid rules he can't see past. His actions are terrible, but labeling him as 'the problem' lets the narrative's own inconsistent worldbuilding off the hook. One chapter he's a monster, the next we're supposed to feel bad for him because the plot needs a fallen ally. That whiplash is more problematic than any single character's flaws.
And Lucien! He gets a free pass as the 'good friend', but his enabling is crucial. He knows Tamlin is spiraling, sees the isolation happening, and his loyalty stops him from any meaningful intervention until it's way too late. That complicity drives the conflict as much as Tamlin's temper. The novel sets up a black-and-white villain in the beginning, then scrambles to paint in grays later, and the characters' motivations get muddy to service that shift. It makes the central relationship drama feel manufactured, not earned.