Eddie Thawne as a child was short and overwheight and was frequently picked on resulting in many beat ups from the bullies. His father was also a senator who closed a factory who many people depended on which didn't improve Eddie's situation and the bullying escelated, until his gym coach took sympathy for him and trained him to fight.

Eddie is described as a "pretty boy" who actually keeps track of his arrests, has a certain wit and appears to be cocky yet is a very efficient cop, who will go to any lengths to catch the criminals. He does have a compassionate side, as he covered Joe's shifts so he could visit a comatose Barry, and is often the first one to comfort the witnesses of the various crimes he and Joe look into. He also disbelieves in The Flash's existence (at first) and thinks anyone who does is a drug user. But when he 'converts' he becomes distrusting of the Flash, especially after he tries to murder him under Roy Bivolo's infulence, and wants him taken down. However since his near-death experience at the hands of his counter, Reverse-Flash, he seems to have changed his mind. He later saved the Flash when he was pinned down, evidencing he sees him as a hero instead of a threat.

He is shown to care for Iris a lot, as he kept their relationship from Joe a secret at her insistence, which, though it annoyed him, he did for 9 months until she was ready to admit it. Eddie is also reasonable, as some dates with Iris have involved places which Eddie isn't too interested in yet goes for Iris. Eddie's working relationship with Joe is fairly stable, as they are both excellent cops who trust each other with their lives. Yet Iris' relationship with Eddie sometimes makes Joe wary. Eddie has a stable friendship with Barry, though the latter isn't entirely trusting of Eddie, mainly out of envy that he is dating Iris, but was suprised to hear that Eddie felt threatened by him when they met. After a year of dating, Eddie was brave enough to ask Iris to move in with him yet suspected that Barry may harbor feelings for Iris though she denied it.

As a police detective of the Central City Police Department, Eddie has proven himself a highly skilled detective. As seen while talking with Barry, Eddie has a degree of fist-fighting skills. He also taught Barry about proper striking methods.