After Barry returned from the alternate timeline he created, most of the Flashpoint changes include characters with slightly adjusted backstories — not entirely new occupations or locations. That's one of the things that makes Tom Felton's new character Julian so mysterious. Who he is and how he came to be working in Central City is unknown. Julian on The Flash is not a DC comics character either. At least, not yet.
When Tom Felton was cast, the character was called Julian Dorn. Now, his last name is Albert. Personally, I don't think that Julian is a villain. While it makes a little bit of sense for "Dr. Alchemy" to be a forensic scientist, this guy seems like a red herring to me. I think the casting of this Harry Potter actor was intentional. Every single year, Harry was convinced that Draco was up to something nefarious. He was only right once, making him worse than a broken clock. Similary, Barry and Julian are instantly suspicious of each other, but I don't think we should trust that as an indication that Julian has a secret identity.
That doesn't mean that Julian couldn't be a character from DC comics. If he weren't British, I would suggest that he could be a Thawne. It's time for The Flash to introduce more members of that family, in my opinion. Maybe he's an AU version of Bruce Wayne's butler — Albert and Alfred are similar, right? Here are a few comic book heroes and villains who could have inspired the "new Barry" on the CW series.
OK, this is a bad guy, but a very silly one so I'm including it anyway. In DC Comics, there is a character and Batman villain named Julian Gregory Day who assumes the alias Calendar Man. He doesn't have much of a backstory, but since the comic book character is an inventor, The Flash could be expanding on the idea.
This one is less exciting, just another forensic scientist from the comics with the same initials as the initial casting, but he does get involved with some criminals in Gotham.
MoviePilot theorized that Felton's character could turn out to be Godspeed, another speedster who worked for the CCPD.
Since the name was changed, you can't ignore the connection to this Albert, who is Dr. Alchemy in DC comics and finds a Philosopher's Stone. However, I'm willing to bet that Alchemy is either a parallel or alternate universe version of Julian, if anything. Maybe he's a relative? Albert does have an identical twin named Alvin in the comics. Whether Julian Albert turns out to be a villain, a her, or just a pesky coworker, it's nice to see Tom Felon clashing with Grant Gustin on The Flash. I look forward to what his character reveals about the time change.