Wait, I'm sorry, I just realized that Keith couldn't really be a good Ladybug? Like, I mean. Okay, yeah. Red's his THING. But Marinette, as Ladybug, becomes the leader, the planner. Her power depends on her ability to come up with a coherent plan. Keith isn't a plan guy, you know? No offense. There are a few people who COULD be Ladybug: Allura, Shiro, and Lance. Allura is the leader of the group, if you include the Alteans. She comes up with the main plans, assigns people to specific jobs, some of the time. She tuned into the others' quintessence and figured out what lions they could be suited for and understands what they can contribute... Mostly. I hope. Shiro would be a natural choice as well. He leads the group and comes up with general plans when Allura doesn't. He can figure out what jobs everyone would best be suited for. Then there's Lance. There are things he does besides flirt: Lance comes up with good plans on the spot, while in combat, using his surroundings, which is a huge part of being Ladybug. Also, I feel his hero origin story would be very similar to Marinette's. If you disagree about the origin story thing, I'd gently recommend rewatching s2e2. So, Lance as Ladybug please. Then the question comes "but, Cat Noir???" Well, that's all up to you, I suppose.