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Stiles starts referring to her as "Mom" immediately after the wedding. He misses his biological mother like crazy, but Melissa's helped raise him for years and he loves her. "You look beautiful, Mom," he tells her at the reception.
Melissa beams at her stepson. "Thank you, Stiles. You're looking pretty handsome in that tux. Now I'm starving and need to eat a cookie, but I'll probably get stopped by a few people and won't be back for a while. I'll see you later."
He laughs. "Good luck!" Stiles waves as she walks away and heads towards the dessert table. He wonders what Scott and Kira are up to and then realizes that's a stupid question. They've probably snuck away somewhere (most likely the bathroom) to have a quickie since they're also newlyweds. They married only three months ago and are definitely enjoying this new part of their lives.
John steps into his son's line of vision. "How are you doing, kid?"
"Pretty good. I'm really happy for you both." Stiles hugs his father and then steps away before he tears up. He promised himself he wouldn't get (too) emotional tonight, but looks like it may already be too late.
John's lips curl up into a smile. "Well, we are definitely happy. I never thought I'd feel this way again after your mom, but I'm glad life surprised me like this." He's so in love with Melissa he can't handle it sometimes.
That's it. Tears leak out of Stiles' eyes and he hugs John again. "I love you."
"Love you too, Stiles." Damn it, now John wants to cry. He pats his son's shoulder and then goes off to talk to a co-worker who is waving at him.
When John and Melissa return from their (short) honeymoon, Stiles jumps from the couch and turns off the TV to greet them. "We weren't even gone that long," a laughing Melissa says.
"I just missed you and Dad, Mom." It actually doesn't hurt to call her that anymore. Stiles feels a pang every time he remembers his biological mom, but it's okay. It surprisingly hurts less and less every day. He'll always miss her, but he's moved on as best as he can. And he's thrilled his father has moved on too. He deserves to be this happy with Melissa McCall (actually, Melissa Stilinski now, something that excites both him and Scott).
"What mess – supernatural or normal – did all of you get into while we were gone?" John wouldn't be surprised if something happened and nobody told them.
"Actually, it was pretty quiet in Beacon Hills these past few days." Stiles is jittery with anticipation about the next crisis and isn't looking forward to it.
Melissa eyes him. "If we find out you're lying, there'll be hell to pay," she warns.
"Yeah, yeah. We get it. I promise you that we're not hiding anything." Stiles heads into the kitchen to grab something to eat since he's starving.
Sitting down for a normal family dinner is a priority for the pack, but they're usually caught up in the latest disaster to do it often. Three months after the wedding, they have one for the first time in six months. "Mrs. Stilinski, this is amazing," Kira raves.
Melissa still gets a chill down her spine every time someone calls her by her new last name. She loves John so much and is thrilled to be married to him. "Thank you, sweetheart."
"We should do this more, and it sucks that we can't." Scott leans over and kisses his wife before grabbing the bowl of mashed potatoes.
"I'm up for this. Mom, this chicken is fantastic." Stiles is a big fan of her cooking and absolutely loves (pretty much) anything she makes.
"I'm glad you all like it." She exchanges a look with John that Stiles immediately catches and latches on to.
"Why are you looking at each other like that?" He's suspicious now and wants to know what they're thinking about.
"Well, you caught us." Scott looks up as Kira grips his hand.
"We're having a baby!" John announces, his smile lighting up the entire room as congratulations ring out.
"I figured it out weeks ago," Scott explains to his shocked brother.
"So did I," Isaac admits, and Derek nods his head.
"This wasn't planned, but we're excited. Now I know this is probably futile, but please don't baby me during this pregnancy. I am a grown woman." Melissa knows that they're going to be overprotective and doesn't know why she bothers. Plus, she's surrounded by a shitload of werewolves (and a Kitsune). They'll be hovering around her until (and probably after) the baby is born.
Stiles never expected this to happen, but he's thrilled. "Congratulations, Mom and Dad." He's already determined to make sure she eats healthy in the next few months leading up to the birth. He wonders how far along she is.
He's the only one with Melissa when she goes into labor since everyone else is dealing with Beacon Hill's latest crisis and he's been put on "Stay with Melissa Stilinski at all times" duty. "God, I forgot how much this hurts. Fuck." Melissa hopes she isn't freaking Stiles out too much.
Stiles is panicking. "Do you need to go to the hospital?"
"Not yet. Stiles, I'm fine – I'm a nurse and have been through this before. Just calm down and everything will be fine." She smiles (encouragingly, she hopes) at him.
Since they're still distracted dealing with this new villain, he's in the delivery room as Melissa gives birth to Audrey Stella Stilinski. "I can't believe you did all that, Mom." Stiles is in awe of her strength.
Melissa rocks the newborn back and forth. "I can't believe I did it twice either. But I have my three kids and I'm thrilled."
"I love you, Mom," he admits.
She grins at him. "I love you too, Stiles."
Stiles and Melissa's bond grows deeper after this highly emotional event, and he's relieved when his father bursts through the door to see his wife and daughter.
When Scott and Kira have their first child eleven months later, Stiles doesn't call her "Mom". He calls her "Grandma". "Becoming an uncle after becoming a big brother is pretty awesome. You feeling okay over there, Grandma?"
Melissa is so excited to meet her grandchild she doesn't even glare at him about the name. "I'm fine, Stiles. I just can't believe I have an eleven month old and am about to become a grandmother. I hope Scott and Kira are okay in there." She can't help but worry about them.
They are. They welcome their son two hours later and he's instantly welcomed in the pack, just like Audrey was after her birth.
Even though Stiles is an adult, he is officially adopted by Melissa several months later. Claudia will always be his mother, but Melissa is too and they want their bond to be legally recognized. It takes Scott a while, but he does start referring to John as "Dad" eventually because he's been more of a father to him than Rafael ever was.