Already have the lore for an Old Buff dude.
(Generalization/Summary) "X Joined the League to show many people what he believes is the true fight. Surviving through the Runeterra wars he is one of the few who fought before the League formed. Now he brings the guerrilla tactics to the League from the Runeterra war. While many of the young champions challenged him within the first week to show off their strength all of them were swiftly defeated, some even asking for lessons."
Aka bad ass dude sick of "young heros" joining the League to show off wants to kick some ass.

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Jesus, these forums are in a fit because we've had some lore based releases lately... Anyone even pay attention to the fact that there aren't any cat people in Runeterra? We've already gotten pretty much all of those monster type bases covered, we don't need to overuse them like Dota2 does. Skeleton: Sion, Karthus. Minotaur: Alistar. Dragon: Shyvana (some Riot posts I've seen hinted at wanting to make a full dragon champ as well). Living tree: Maokai. Beastial humanoid: Warwick, Renekton, Nasus. Demonic/arcane being: Kassadin, Morgana. I don't really know what the green guy is (nor do I remember his name), we don't really need him in game, we also don't need spiders, but we might get one or two at some point.

Varus is exactly what you're describing: a more "interesting" human. Darius and Draven were released in succession due to the devs wanting a lore based release. Jayce might be a "generic" human, but his kit would be hard to work in to any other sort of character. Let's focus on stuff that actually matters in the long run, gameplay, quality. Draven Varus and Jayce are all some of my favorite champions in the game, simply due to their increase in quality (animation and design) and unique kits. Draven took a new spin (get it? ) on the ranged AD global ult, and has a unique Q that I never would have thought of, and adds all kinds of fun to the gameplay of an AD carry. Varus adds probably only the second utility based AD carry into this game, and while he's relatively simple, I feel like all of his spells sync together quite well, and a well played Varus is quite a sight to behold compared to an average Varus. Jayce has, quite simply, the most variety in gameplay of any champion in this game. He's quite similar to Invoker in this respect, but he doesn't bring as much of a burden of knowledge. His ranged and melee kits might be separated, but they sync together in so many different ways he can seem like a different champion all together if played differently.

Now, Darius is a little simple, but that's what the design team was going for. At the moment, I feel he needs some re-balancing of his damage and mana costs/CDs. He's a little ridiculous, but he adds some simplicity that is honestly lacking in a lot of recent releases (That's a good thing, but simplicity is also needed, especially for newer players). Darius' entire purpose is to be a powerful, scary ass dude with nearly no other personality because he is simply a dog of war. Riot was very successful in this respect.

Now to snap back to your wants to round off this post, the monsters will come, and probably very soon (if not 101, then for sure 102). I want to say 101 is a female human (possibly monster-y), but 102 I'm almost positive is a monster of some sort.