Eobard Thawne a.k.a. the Reverse Flash is the most iconic villain in the Flash and one of the best villains in the Arrowverse overall. Not one but two actors play him: the first being Tom Cavanagh and the second being Matt Letscher. Both of these actors succeed in bringing the character to life. And while Letscher has had fewer episodes to shine as the character, he like Cavanagh has given the character a unique distinction. Both have similarities and differences in the character that are worth looking at.
Both versions of Thawne are straightforward maniacs willing to go to insane extremes in order to achieve their goals. Both versions of the character also think themselves superior in terms of speed and position of power with the Flash and his own allies in the Legion of Doom. In getting what he wants both versions have selfishly manipulated his team in doing so. In the form of Harrison Wells he kills Cisco in an alternate timeline to prevent the latter from spilling his secret, nearly kills Caitlin’s fiancé, and manipulates Barry into improving his speed. In his original form on Legends of Tomorrow he outright pits Damien Darhk and Malcolm Merlyn against one another and withholds the truth about his nonexistence from both of them. In both versions he is shown to be quite secretive about himself. While both versions have a level of insanity they have a genuine motivation outside of just being better than the Flash. In the Flash Eobard just wants to return home and in Legends he wants to live.
While in the form of Harrison Wells, Thawne’s appearance-stealing device also caused him to inherit some of his traits. Despite the fact that he never knew the real Harrison Wells’ wife Tess Morgan he still claims to get teary-eyed over her death. In the 15 years he has spent in Wells’ form he is a lot calmer and subdued in forming his plans. The rage he has in his true form only seems to pop up on occasion. He also has a great regard for the scientific community. Even when he kills Cisco in the alternate timeline in Season 1 Episode 15 of the Flash, you can feel the care and sadness in his voice he has for Cisco when doing so. And despite his hatred for Barry he still develops a care for his nemesis as a student and even a son. He also was willing to risk his own life for Team Flash as seen with Farooq Gibran, protecting Grodd from General Eiling, and help defuse Firestorm. As Wells he utilizes the vast knowledge he has gathered over the last 15 years to silently kill and methodically silence and destroy any threats to his plans. Ultimately as Wells he goes back and forth between his insane desire to return and a compassionate and honorable man.
In Legends of Tomorrow (and a Flash episode pre-dating it) following Flashpoint he is back in his original form. However he is not without some level of humanity. There is a scene he has with Ray Palmer in Season 2 episode 14 where he mentions missing working with Caitlin and Cisco and has a genuine fear for the Black Flash which he fears more than Time Wraiths. Despite ruining the hero’s lives upon acquiring the spear, he still used it to stop global warming and polar bear extinction. However any sort of care he had for his fellow allies is gone. He is completely enraged and twisted unwilling to let anything or anyone get in his way. His morals are low to the point that he had little if any remorse for allying with 1942 Nazis providing them with his meta-human bio molecular enhancer to help them win World War 2 only to steal an amulet. He also erased Rex Tyler from the timeline despite calling Barry out on creating Flashpoint. This Thawne also shows pleasure in toying with his enemies. He taunts Barry upon realizing why his memories remain intact while Barry is losing his. He also spares the Legends and the Legion of Doom in his new reality to humiliate them to live with the knowledge that they ultimately failed. Thawne here is also far more direct in his actions as seen in the finale when he rips Raymond’s heart out instantly.
Thawne, regardless of who is playing him has a great deal of layers to him. As Wells and himself he is hell bent on achieving his goals by any means necessary but also retains a spot of humanity. Both are insane but are different in how they show their manical nature. Regardless of who plays him every time he appears however, never will it not be good to see him.