Currently I thought of these 3:
1. Warwick - There is a well-known rumor going on with most people saying they see the similarities between him & Vander
2. Ziggs - Arcane's version might be a clone of Heimerdinger as he hangs out with Ekko in the last episode of the 1st season so why won't it happen?
3. Twitch - The rodent that Singed experimented on in the 1st episode is probably him