radius-of-records reblogged your post:
FINE TRAIN BUT LANCY BBY NO GET AWAY FROM THAT CURSED VOLCANO IT BRINGS NOTHING BUt PAIN AND BAD MEMORIES
//Cries let me ramble in headcanon then
It's obvious that Cerise brings a lot of bad memories to Lance. The first times he and his Pokémon trained there after his time in Johto, Sinnoh and back to Johto, he probably ended up feeling like shit instead of enjoying it. However, as times passes, even if he can't avoid that heartache of being in that place where he was a monster, he still loves that island.
It's true that not only emotionally, but physically it doesn't stop damaging him, but he can't just stop himself from training there. He doesn't do it often, though. Once every two weeks or a month (mainly because probably Cynthia and his Pokémon stop him). But he does, because even if it's got memories of a time he'd want to erase, that island was the perfect place to train and to make the bond with his Pokémon even stronger and unbreakable.
However, he always trains only in the crater. Cerise has never erupted again since the battle with Yellow, and he's not going to burn the flowers left by the Megavolt that destroyed and saved him after all.