Presently we don't have any Champions who have had children (besides Kassadin, but he doesn't fit the trope), or who act at all with that motherly instinct to protect one's young. I don't think it's an angle that's been explored yet (the closest you can get is Braum, but he's more the "jolly guy"), so it'd be a neat if Riot took a crack at it.
I think this is what Riot was going for with Tibbers' enrage mechanic, specifically the part where he enrages when Annie dies. He's even a bear.
Actually there is one champ who is a parent.
But he is a guy 
so if anything he'd be a candidate for the "papa wolf"-trope.
Anyway I agree,someone who looks out for the younger generation is pretty much missing in the game.
Leona did use to have this as a big part of her lore,but that was heavily toned down in the new one(it is still there to some extend with her sparing the golden boy,but it isn't central to her anymore).
Braum’s Mother, maybe? Mother always said: don’t lose.
I think this could be a really cool mechanic. Like a berserk support, link with an ally or have a sheild on them or something and if the get cced or maybe take a big chunk of damage, momma bear would like jump in front of them and do a flurry crazy bear slashes and do tons of dmg. Itd be pretty fun to play i think.
A back story idea could be like she lost a child to something or other and now shes protecting other people instead
I don't know what this says about me, but the 1st person I taught of when reading the title was 
.
Is this something we actually want?
I think Rek'sai was supposed to have this kind of trope in a Void-y horror kind of way, since she is mother to the other Xer'sai. I could have sworn her old bio said something about being protective of them as they were hunted down or something. I can't remember where I got that from, though.
What about 
man he tryna save his jungle friends from the enemy team and he has daisy to assist
The motherly or protective champs are mostly male but...
Skarner, Rek'sai, Anivia, Aurelion Sol, Ivern, Soraka are the most direct ones Illaoi, Braum, Zac, Galio would definitely fall under this category if they had anything they could consider children. Instead they're like cool aunts and uncles
Lamb, Karthus, Azir, Lissandra, Viktor have relationships that don't match with any type of human relationship but with enough mental gymnastics you can definitely compare them to a mother-child relationship
An AD support where you mark your ADC (think kalista black spear), and when they die, you just go ape shit and beat the living hell out of the enemy.
Also could work that the lower your marked teammate is, the more damage you do, rather than the post-death effect.
They'll probably add 
's mom at some point.
