That was the first time Toya tried to murder Shoto; we already know it wasn't the last. In My Hero Academia's recent War Arc, Dabi sought to murder Shoto in front of Endeavor for the same reason as all those years ago: causing the maximum amount of pain to the one who hurt him.

Did Dabi kill Shoto?

He also admits to originally wanting to kill Shoto once he had become successful in his hero career, thinking of him as Endeavor's little puppet. This reveal causes Shoto to feel shocked and horrified upon seeing his oldest sibling as a nefarious villain.

Does Dabi want to kill Todoroki?

Dabi claims that he views Shoto as nothing more than their father's "little puppet" and that he planned to kill him during his hero career, but this was only because this was part of his plan of ruining his father's legacy, until his father became the No. 1 Pro Hero.