I love the Malcolm Thawne storyline because it makes Eobard Thawne the perfect foil for Wally West.
Eobard Thawne is the great (x4) grandson of Malcolm Thawne, making him Barry Allen's great (x4) nephew, and he grows up absolutely idolising the Flash, despite heroes no longer existing. He collects memorabilia, he owns his biography, he replicated the accident that gave Barry his powers, and he went back in time to try and meet Barry. However, when he travels back in time, he accidentally ends up coming back to the time after Barry's death, where Wally is the Flash. He then finds the Flash museum, and discovers the identity of Professor Zoom, Flash's greatest enemy, a name lost to time, and it turns out to be him. He is his hero's greatest enemy, the one man the Flash killed, and this makes him lose it. He thinks he is Barry Allen, and when he eventually remembers he's not, he hates Barry for killing him, thus signaling the beginning of the Reverse Flash. His legacy started when he found out Barry killed him.
Wally West, on the other hand, is the nephew of Iris West-Allen, making him also Barry's nephew, and, like Eobard, he grows up idolising the Flash. His room is filled with flash merchandise, he wants to meet him, he is the president (and sole member) of the Blue Valley Flash fan club, and, despite his parents insistence that hopes and ambitions are for dreamers and that Wally needs to face reality, he dreams of being like the Flash. And he doesn't just become like the Flash, he actually becomes the Flash. He dedicates his life to living up to the legacy of Barry Allen, so much so he is left with a bad case of imposter syndrome. He needs to carry on for Barry, he can't let the Flash die along side him, he must continue his legacy, regardless of if he believes he lives up to it or not. He will bring up Barry any chance he gets, his biggest fear is Barry not believing in him, and the pedestal he puts Barry on slows him down at various points. He has said multiple times that his life started at age 10, his life started when he gained access to the speed force and became Kid Flash, his life started when he met Barry.
They're truly two sides of the same coin, they're both Barry's nephews who worshipped the Flash as kids, only one grew up to become his greatest enemy and his reverse, whilst the other grew up to carry the torch after his death and become everything he wanted the Flash to be. I will always love the Malcolm Thawne storyline for this
(Also I think it's fun that Barry meets one of his relatives from the future and they absolutely hate him. It's tragic and perfect. Pair that with him not getting to meet his twins and Bart just not really caring about him, his luck with his descendants is awful and I love it)
