I keep seeing people say that house md is serious after s4 ends. which i definitely disagree with. yes the show is darker from that point on, but the show is pretty dark as a whole, especially from the last half of s2. it's not as happy and silly and goofy as people think it is.
to be honest, I think the only reason why the show is darker in s5 onwards (at least, the only thing that applies to all of those seasons) is the fact that the antagonist is house, as opposed to Cuddy/Tritter/Vogler. in s1-3 (and even 4 to an extent) an external character stops house from reaching his goal or causes him to suffer, think Tritter arc, Vogler arc, and so on. but from 4x15, the person causing the most harm to house is house himself. House (unintentionally) kills Amber, driving away his best friend. He then drives himself into the psych ward. His compliance in the murder of Dibala (however justified it may have been) caused him to lose one of his (former) favourite employees/puzzles forever (yes, I think house favored Cameron to Foreman until Foreman handed in his notice). Then, he suffers due to the breakup with Cuddy. Then by giving himself rat meds. Then by giving himself surgery. Then by crashing into cuddy's house and sending him to jail. S5-S8 is only dark because House causes his own suffering.
