Buffy & Dawn Are Still The Cutest Sisters, As Sarah Michelle Gellar Proved With This Sweet Birthday Instagram — PHOTO

Little Dawn Summers — well, Buffy The Vampire Slayer actress Michelle Trachtenberg, that is — is all grown up now! I can't believe it, and neither can Buffy herself, show star Sarah Michelle Gellar. Trachtenberg turned 30 on Sunday and Sarah Michelle Gellar posted the sweetest birthday wish for her former on-screen sister, proving they're still friends and that Buffy and Dawn's sisterly bond still exists. Gellar's Instagram post is a collage of photos of the two actresses, which include pics from their Buffy days, ones of Trachtenberg as a little girl, and some of the duo all grown-up. "I met you as a little girl on [All My Children] and have continued to watch you grow," Gellar wrote in the caption. "You may be taller then me now, but you will always be my little sister. You have the key to my heart." Too. Cute!

Gotta love the Buffy reference Gellar slipped in there, too — in the fifth season of the show, Dawn is a mystical Key in human form, and was made to be Buffy's sister so the kick-ass slayer would protect the valuable treasure. And it works well as a metaphor, too, doesn't it? Family is a great treasure that needs protecting. In the years since Buffy ended, Gellar has starred in Ringer on the CW and The Crazy Ones on CBS; Trachtenberg appeared on the CW's Gossip Girl as Georgina Sparks and has also appeared in Killing Kennedy and Sleepy Hollow.

But no matter where their careers have gone, it's clear that the former co-stars bond is still as strong as it was all those years ago. Let's take a look back at the best Buffy and Dawn moments from Buffy the Vampire Slayer.

When Dawn Is Introduced In Season 5

Dawn is pretty randomly introduced in Buffy's fifth season, and, by randomly, I mean that previously, Buffy does not have a sister. Suddenly, the Scooby gang and even Buffy's mom Joyce are accepting the new teen as if she's been there all along, like how '90s sitcoms never acknowledged the entrance or exit of certain characters. It's a few episodes before viewers learn the truth, but this bit of foreshadowing is awesome.

When Buffy Sacrifices Herself For Dawn

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This comes at one of the biggest moments in the series, when Buffy realizes that indeed, "death is her gift." Instead of Dawn getting thrown into the portal to seal it, Buffy sacrifices herself, because Summers blood is the Key and she can take the place of her little sis.

When Dawn Calls Out Buffy On Not Being The Best Older Sister

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In the wild ride that is Season 6, Willow gets hooked on magic and is the worst babysitter for Dawn, crashing a car and breaking Dawn's arm. Dawn, however, blames Buffy, because Buffy's been consumed by hooking up with Spike and hasn't been there for her like she should.

When Glory Kidnaps Dawn

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In one of the saddest (and trippiest) episodes of the series, Buffy goes completely catatonic when Glory captures Dawn. At this point, Buffy's been through so much — she came back from the dead, her mother Joyce unexpectedly passed away, and now Dawn is gone? Too. Much. "The Weight of The World" is also an episode that shows us that even though Dawn may not have initially existed before Season 5, Buffy has happy memories of her sibling, including one of her parents bringing home her baby sister from the hospital.

When Buffy Realizes Her Little Sister Is All Grown Up

It's like one day Dawn was writing in her journal and being cute, then the next, she's dancing very suggestively at the Bronze with a football player (much like Buffy once did). Of course, we soon learn that this football player named R.J. has a certain effect on women in this Season 7 episode.

Today, Michelle Trachtenberg is all grown up for sure — hitting the big 3-0 — but it's so great that she and Gellar still retain that sisterly bond. After all, they went through a lot together (on-screen) on Buffy.

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