All ninja champions lose one health for each other allied ninja. (The Ninja buff they have) When Graves uses smokescreen on an enemy Nocturne, he will sometimes either say, "Who's in the dark now?," or, "I've got yer darkness." Leona's Sunlight deal one less damage to any champion wearing sunglasses. (This includes skins) Skarner will make a Pokemon reference if he's standing in a bush long enough. Nunu will drop two souls when killed by Thresh - One for the yeti and one for Nunu. Vi and Caitlyn have a few interactions with each other, including cosmetic buffs and debuffs, bonus gold when they help kill the same champion, etc. Volibear gets a special cosmetic buff when opposing a Zilean, and also gets bonus gold for killing one. Zilean has the same, but inversed. Zyra and her plants get larger when hit by Leona's sunlight, and when Maoki gets close to her, she gives him +1 movespeed.
As a blood elf male, his weak point is his ovaries. Punch him there. -befo72