It was around the time of Kench. There was this big idea that he was going to have a link kinda like how Kalista dose and there was going to be like an armor thing were it burrowed into you and gave you a stat buff for a time.
Am I the only one who remembers this?
Hm I think i know what you mean,there was talk about a possible champ who could kind of equip itself to an ally.
However that is only a very rough sketch for a very complicated ability(as there are huge amounts of possibilities for such an ability,like what would be the benefits of the ability?could the parasite still use abilities?does he get new ones?would he be immune to damage while inside an ally?,etc.),so it could take years for such a champ to be developed.
I mean a good comparison would be 
.
His whole design process mostly started with the idea of making a champion who can eat others.
This idea was originally planned to be gnars ultimate(and might have been around even before that),so it took them roughly a year(maybe even more) for them to create a champ with such an ability.
And while devour is a powerful ability,it isn't that complex compared to a parasitic champ like you describe him.
