Cobie Smulders, Neil Patrick Harris, Becki Newton

Forget the mother! (For now anyway.) How I Met Your Mother will finally answer the series' second-biggest mystery on its Season 7 finale: Who is Barney marrying?

Since last season's closer, in which Barney (Neil Patrick Harris) was revealed to be the groom at the wedding where Ted (Josh Radnor) meets the titular mother, Barney started out this year by rekindling his relationship with Nora (Nazanin Boniadi). But Nora — and the chances of her being Barney's bride — was soon out of the picture after he cheated on her with Robin (Cobie Smulders). Barney broke up with her to be with Robin, only to see her pick Kevin (Kal Penn) instead. After a pregnancy scare with Robin, it seems The Barnacle has now found domestic bliss with live-in gal pal Quinn (Becki Newton).

Finale Preview: Get the scoop on How I Met Your Mother and 38 other season enders

But could Quinn be the one swapping vows with Barney? Before the flash-forward reveal on Monday's one-hour finale (8/7c, CBS), the couple gets stopped by airport security when Barney refuses to open a metal box that surely must contain some precious cargo. Or is Robin the bride? Co-creators/showrunners Carter Bays and Craig Thomas have always insisted that Robin and Barney's complicated story is not over. Or could the future Mrs. Stinson be somebody else?

Let's break down the contenders:

Robin
Why it might be her:
Robin is Barney's bro and his first meaningful relationship as a suit-loving womanizer, and there is unfinished business between them. After they took forever to get together, they split — because two awesomes cancel each other out — before we could even say "wait for it." They were thisclose to getting back together this season, but Robin chose to instead shatter Barney's heart into a million little pieces. Timing has always been their issue, but since the wedding is "a little ways down the road," maybe they will have gotten on the same page by then.

Clues:
Robin told her imaginary children that Barney's their father. She is the only one of the gang we have yet to see in the flash-forwards to Barney's wedding. At the wedding, Lily (Alyson Hannigan) retrieves Ted, the best man, for Barney and later tells Ted that the bride wants to see him too, which suggests that Lily is the maid of honor (or at the very least part of the bridal party), and she would be the obvious choice if Robin's the bride. In Season 6, Robin asked Ted to be her best man if she ever got married — could Ted be pulling double duty as best man? We know Ted meets his wife at the wedding, and if she turns out to be Barney's heretofore unseen half-sister Carly (she's in college — was she in that economics class Ted accidentally taught?), then "Aunt Robin" and "Uncle Barney" would literally be his kids' aunt and uncle.

Why it might not be her:
Robin was the group's resident, career-oriented single gal/commitment-phobe, adamant about never getting married or having kids. Her feelings have wavered over the years, but she's finally enjoying some professional success now, which means she could put her personal life on the backburner while she focuses on turning into the world famous journalist Future Ted says she will be. Robin never became a mother, and while we don't know if Barney became a father, we do know that he wants kids. (You gotta pass on those laser tag and magic skills to someone, right?)

Fall TV scorecard: Which shows are returning? Which aren't?

Quinn
Why it might be her: Quinn is basically the female version of Barney. The feisty spitfire stripper can match wits with him and is not afraid to call him out on his mischievous ways — or carry out some of her own. Even Marshall (Jason Segel) says they're "perfect for each other." Barney has fallen quick and hard for Quinn, and she's done something none of his past love interests — not even Robin — has ever done: move in with him. Also: He's farted in front of her.

Clues:
When Barney asks what it would take for Quinn to give up stripping, she says getting married. She's already refused his request to quit, along with the GNB gig he offered her, and with Barney's increasing concerns about Quinn's day job (or should we say night?), a wedding doesn't seem completely out of the question. And then there's the fact that Barney's told her that he plans on being with her for a long time.

Why it might not be her:
Well, Barney and Robin fanatics might start a riot, first of all. While Barney maintains that he's completely over Robin, Quinn could still be a rebound, hence the fast progression of their relationship. Plus: Why would Quinn ask to see Ted moments before she's about to tie the knot? Not that she can't see him, but Robin asking for him is more logical. It also would make much less sense for Ted to have started this whole mother story by telling his kids how he met their Aunt Robin if the wedding where he met the missus was Quinn's.

How I Met Your Mother's Becki Newton: Quinn has gotten to Barney's heart

Someone else
Why it might be someone else:
If Bays and Thomas want to go for the shock factor, this would be the way to do it, whether it be with Nora, Barney's first girlfriend Shannon (remember her?) or a new lady entirely.

Clues:
None, really, unless you count Thomas saying at the beginning of the season that there we would be "a bunch of different candidates." (There wasn't.)

Why it might not be someone else:
Mother prides itself on meticulously crafted storytelling, planting hints here and there that will eventually reveal the whole picture. The evidence so far has pointed to Robin or Quinn, so for the bride to be someone else — especially a new person — would almost be a slap in the face to fans who've been dutifully studying the puzzle pieces. On top of that, Shannon (Katie Walder) has rarely been mentioned since Barney's "origin" story episode in Season 1, and we can't really see Nora, who had her heart broken twice by Barney in a year, forgive him for cheating and marry him in the next two years (Barney's wedding happens by 2015 since Ted has his daughter by then.)

Who do you think Barney is marrying?

How I Met Your Mother's one-hour finale airs Monday at 8/7c on CBS.