The last few of episodes of Pretty Little Liars Season 4 have been some of our favorites of the season, and we know why: Mona (Janel Parrish), who'd been MIA for a big chunk of the season, is finally back in a big way, and it's glorious. In fact, her disappearance and subsequent triumphant return convinced us of one very important fact: Pretty Little Liars is better with Mona on screen.

We find it hard to believe we ever doubted the genius of making Mona the original "A", because it was so clearly a great move in the long run. So, to honor the awesome that is Mona Vanderwall, here are five reasons Rosewood is more interesting when she's around.

You never know if you can trust her. Yes, Mona is hardly alone in this department — we can count the number of truly honest Rosewood residents on one hand — but what makes her brand of untrustworthiness so fascinating is that we know she's evil. She's not a suspect, a potential killer, a question mark — she is "A". And yet, we can't help but find ourselves believing her when she says she's on the Liars' side now. We know it's stupid, we know she always has her own agenda, but we can't let go of the idea that part of her cares. That means watching her is never boring, because we never know what to expect.

Her relationship with Hanna. Speaking of Mona caring, her relationship with Hanna is definitely one of the highlights of the show, especially during Season 4. If you believe Mona, their friendship is what drove her to her twisted, stAlking ways in the first place, and this season she seems to genuinely want to reconnect with her former BFF — and the fact that Hanna begrudgingly trusts her out of necessity just adds another layer to this complex relationship. We could watch these two dance around each other all day.

She's smart. It's always good to have a chessmaster running around manipulating people — or fighting Red Coat, depending on the day — and Mona is one of the most intelligent characters on the show. She can think ten steps ahead, and she knows how to poke and prod other characters to get exactly the reaction she wants. We wouldn't want to hang out with her in real life, but it sure is fun to watch her work.

She's a snark queen. Pretty Little Liars is known for its witty one-liners, and Mona has some of the best of them.

Janel Parrish is fantastic. None of this would matter if Janel Parrish weren't able to bring Mona's layers to life convincingly. Somehow, she manages to make Mona's pain as convincing as her evil mastermind smirk; plus, she has chemistry with just about everyone. This young actress continues to impress week after week.

What's your favorite thing about Mona? Let us know in the comments below!

Catch the next episode of Pretty Little Liars on Tuesday, August 13, 2013 at 8 p.m. ET/PT on ABC Family.

Rebecca Martin is an Associate Editor at Wetpaint Entertainment and our resident Game of Thrones, Breaking Bad, and genre TV expert. Follow her on Twitter and Google+!