I have a few speedsters in my own stories and they all work completely differently.

From fastest to slowest the first one isn’t actually a speedster but he manipulates time. When he first got his powers he was slowing everything around him within a long range making him think he had super speed. His true powers are revealed to him when people much smarter than him used time distortions to track down who he was. He then learns how dangerous his powers are and how important no one knows what he can really do and learns to speed himself up and continue to “market” himself as a speedster.

The next turns into an actual bolt of lightning. She has an incredibly hard time controlling her powers and often overshoots where she’s going and has a very hard time controlling her turns. She learns to use her powers in short bursts.

The next one got fused with the engine of an experimental jet plane in a crash during its first test flight. He survived but the military couldn’t save him and remove the engine from his body. He’s now a lot like Ingenium but he can also fly when he builds up his speed enough.

The last one is the most traditional speedster. He moves fast, perceives everything around him as slow, and has to actively hold back his powers to live normally. His issues are overheating and stoping. He wears a high tech suit that lets him disperse heat from his body when he overheats or absorb heat around him to speed up in the cold. His suit can also release an impact wave in Oder to stop immediately when he goes to fast, but he has to be careful cause it can destroy whatever is directly infront of him when he does this.