You looked in the mirror, and saw what appeared to be a green dragon standing in the reflection replacing you as a whole. You then looked around seeing nothing was there, and nothing had changed. You then looked at the mirror again, and slowly walked towards it motioning to touch the glass. However as you walked towards it you tripped on a wooden board sticking up from thr ground slightly, and fell towards the mirror.
Instead of it shattering like you expected, you were actually pulled into the mirror, and into an alternate reality. You didn't know what happened after that except for the fact that you were knocked out by something as you collapsed. The last thing you remember seeing before being knocked out completely is the dragon looking at you generally shocked at what happened. When you awoke you were shocked, you were in the mansion, but it seemed relatively new, like it was just built. You then looked down to see you were inside a nest, and you were covered in green scales, and were naked.
The second you were about to freak out the dragon you saw in the mirror clamped your mouth shut, and you realized you had a muzzle. The dragon then gave you a slightly concerning look, and actually spoke to you saying,"Hey, I see that you have found the portal in the mirror, and all destroyed it on accident. Basically I am you, and you are me, I'm just an alternate version of you that lived in the past that will become you when I die. The only thing is..."