How can I morph an object into a liquid and back to a different object? I suppose I found nothing about because I don't know the proper technique name/terminology.

I'm working in my first videogame, an adventure-suspense walking simulator. I need to know techniques/tools/modifiers/plugins names about the next example.

I have a genetically modified character who can transform into a liquid, and reverse, the sequence it's he has one single hair of himself, drop it in a table, then the hair transforms into a grey liquid drop, and the drop transforms progressively into a flower.

I need that technique in reverse as well, to transform some liquids coming from different places progressively into the characters body.

Can someone give me an approximation about what I need to know? Thanks in advance.
I think the terminology you want is "Fluid Control".  If you google "Blender Fluid Control", you will find some tutorials on YouTube that will make fluid crawl up onto a shape (Suzanne for instance).  Then I think the compositor is your friend.