A complete change, Umbreon to shadow Umbreon tf

One day, an Shiny Umbreon was walking down the path as normal, having a lovely time when he spotted an unusual, moon-shaped gem.  "Hmm, what is this?" he asked himself as he picked it up, expecting nothing to happen, when in fact something very strange did happen, the gem started to absorb into his body.  As he noticed this, he cried out loud "What the hell?  What sort of gem is this?", but this wasn't the only weird thing that happened to him.

As soon as the gem had been fully absorbed into his body, his rings turned black, seeming temporarily to disappear.  "Wait, what has happened to my rings?  Where have they gone?" He asked himself as this happened, very confused.  After this tho, his rings appeared again as his main body fur turned red.  "Ah there they are, wait, what is happening to me?!" He cried aloud in helpless confusion.  Finally, his eyes suddenly hurt massively as they turned fully red to blend in with his fur, causing him to instinctively close them, tears pouring out of them "GAH!  P-Please, just stop the pain, it's too unbearable" he said as the final visual changes happened.

After this, his head then hurt massively, causing him to cry more as his mind started to empty.  "Noooo, not my memories" he cried as his memories slowly emptied.  As soon as they empty, he opens his eyes and wipes his tears away, completely mindless.  After this, new, evil memories flood into his mind, causing him to cackle evilly.  "And now for my next victim" he says in his new mind, picking up a bunch of gems and searching for his next victim, which is you.