Since returning from the dead, Red Hood carries a grudge against his former mentor, Batman. But, rather than blaming The Dark Knight or Joker for his gruesome death, he blames himself.
Infamously, during the "Death in the Family" story arc, Jason Todd discovers that the woman he had long believed to be his biological mother was actually a stepmother. In an effort to learn more about his biological mother, he travels to Ethiopia (which has since been retconned into Qurac) for more information and meets Sheila Haywood, an aid worker and Jason's birth mother. However, The Joker is able to blackmail Sheila into bringing Jason directly to him. In Joker's captivity, Jason is beaten senseless with a crowbar and killed in a warehouse explosion. Nearly two decades later, the former Robin is resurrected by Talia and Ra's al Ghul's Lazarus Pit. Since returning and adopting the Joker's former pseudonym, Red Hood, he's vocalized his resentment for both The Joker and Batman. While his resentment is understandable, he doesn't blame either for his death, not even his murderer.
In Red Hood and the Outlaws (2016) #10 by Scott Lobdell and Dexter Soy, in an effort to save Artemis, Red Hood returns to Qurac, the place where he died. As a result of a concussion, he momentarily gets lost in his own head. While he's getting tortured in reality by Qurac's General Heinle, his mind transports back to the night Joker murdered him. During this instance, he reveals that there's only one person he blames for his death: himself.
For years, Jason has hated Joker for killing him and hated Batman for never avenging him by murdering the Clown Prince in return or even preventing his murder. However, for all the anger and hatred he carries towards both men, it's bittersweet to think that most of his anger (along with regret and blame) is directed towards himself. He blames himself because, in his own eyes, he walked into his own death by going alone. It's especially bittersweet knowing how alone his origins were.
When Batman first found Jason, the boy was abandoned by his father while his stepmother was addicted to drugs, which forced him to fend for himself. Batman came into Jason's life as something of a godsend. Jason finally had the companionship and the father figure he never had but discards him to run off alone on his own adventure in search of his mother, and it cost him his life. Now that he's regained that life, Red Hood is forced to carry the guilt and "what-ifs?" in his head about how he could have gone about the mission differently.