When thinking of Hanna's new husband, words like integrity, smarts, and diplomacy probably come to mind. However, there's one clue that could mean Caleb is A.D., so it might be time to revise your opinion. This came courtesy of a Pretty Little Liars fan theory on the show's fan wiki, in which user Cast1e06 put forward a case for A.D. being Caleb. There are a lot of different reasons they cite as evidence for this, but, for me, the standout moment is when they argue that Caleb is Bethany's half-brother and that "Caleb's story says he was put into foster care at age 5, but that was actually when he was sent to Radley for the bathtub incident."
After all, when you think about it, most of the other characters grew up around each other. It's easy to suspect Ezra because, much like Caleb, he lacks an origin story and he's a king of reinvention, giving himself a new name so he wouldn't be associated with his wealthy family. But there's no reason why we shouldn't apply that same suspicion to Caleb, since there are a lot of years in his biography where we mostly have to take his word for what happened.
The last time we got a big reveal, courtesy of CeCe/Charlotte, we learnt that a character who had seemed a little skimpy in terms of backstory and didn't have any obvious connection with what was going on actually had an elaborate history that connected them to Alison. So, it seems worthwhile to look to characters who have to be taken on good faith that they are who they say they are — especially since there appears to be a spare baby that's unaccounted for. (Let's not forget Doctor Cochran's reveal that he delivered two of Mary Drake's babies, which some fans argue could be interpreted as two of multiple babies.) Sure, Ezra's past is similarly sketchy, but at least we've seen figures from his past, like Jackie or even his mom Dianne Fitzgerald, turn up. In terms of figures from Caleb's past or family members, even the one character we meet, his "uncle," isn't who he seems. Conveniently, the man turned out to be his dad.
There are other clues, of course. There are very few people in Rosewood who have had the innovative nature and smarts to build the board game (let's be real, it's Mona, Lucas, at a push, Spencer or Melissa, and, of course, Caleb). There's the fact that A.D. is likely to be the father of Emison's child, meaning that they're probably male, which, again, limits the options. And there's the fact that we know via the series' showrunner that the person who plays A.D. asked I. Marlene King not to reveal their true role to the rest of the cast because they didn't want to affect their scenes, which suggests they're a series regular. But, arguably, we know less about Caleb's past than any other lead male character aside from Ezra. And that makes him a strong contender for the role of the show's greatest villain.