Who

Who is a former gangster and childhood friend of Ladd Russo. He becomes Fred's nurse/helper after he helps Who at the incident of The Flying Pussyfoot. Contrast to many other unique psychos in Ladd's group, Who actually cared for Ladd and Lua yet was too cowardly to take the initiative. He also knew of Graham Spectre. Due to the absence of Fred, Who is heavily implied to have been killed in the events of the anime in contrast to the novel.

Personality
Tough as he sounds, he is infact a coward as admitted by himself. His biggest regret was not helping Ladd cope with the loss of his first fiance Leila, which is noted by the former gangster to be the result of Ladd's current psychotic episodes.

1931 The Grand Punk Railroad
Who is first introduced as part of Ladd Russo's gang of psychos that would be part of the heist to gain money and commit mass murder on board The Flying Pussyfoot. Later into the book, Who is wounded during a scuffle with the Lemures and the mysterious Rail Tracer and meets The Grey Magician. After deciding that he had enough of the violence and is happy to be alive, he turns a new leaf and abandons Ladd's gang when the storyline is over, becoming Fred's assistant/Nurse.

1931 Another Junk Railroad - Express Episode
While nursing Jacuzzi, the delinquent deduced that Who is infact part of Ladd's gang. Who, despite being an associate, corrects Jacuzzi that he is not a part of the Russo family and does not intend to sell him out to the Chicago based crime family. Jacuzzi wanted to learn more about Who and the former gangster reitirated a past occurence where he was bullied as a child and a Senator's daughter named Leila and a young Ladd would help him overcome his cowardice in order to get back at his bullies. He saw Leila and Ladd fall in love with plans to elope much to the fury of Leila's father.

The next day of that fateful night, Ladd returned as the psychotic murderer Jacuzzi and Who knew today. Leila was confirmed to have died that night of their elopement but Who vehemently denies that Ladd killed her, for he was truly in love with her before Lua Klein. Who concluded that if Ladd had indeed killed Leila, then he and the others could have died easily on The Flying Pussyfoot and dismisses Ladd's psychosis as merely a coping mechanism to overcome his grievances of losing Leila.

Trivia

 * as Fred was absent in the anime, it can be heavily implied that Who was killed during the Flying Pussyfoot incident as the police implied in episode 1 that Ladd and Lua were the only survivors.