Christian Slater Opens Up About 9-Month-Old Daughter's Milestones: She's a 'Wonderful Spirit'

Twenty-one years after becoming a dad for the first time, Christian Slater is enjoying all the sweet moments a newborn brings to the family once more.

The Dirty John: The Betty Broderick Story actor, 50, and his wife Brittany welcomed their first child together, a daughter, last August. And now, amid the ongoing coronavirus pandemic, Slater, Brittany, their baby girl and Slater's 18-year-old daughter Eliana Sophia are social distancing at home with their newest family member — who is keeping the couple "very busy."

"I feel for everyone that is being affected by this, but getting the chance to spend some time with family, spend time with my older daughter who's been with us before she goes off to college, [is great]," Slater tells PEOPLE.

One of his favorite moments, he adds, has been "getting to see my daughter start crawling." And, as the proud father explains, "We're on hold waiting, at any moment, for either 'Mama' or 'Dada.' "

As for whether he's trying to get the "Dada" angle going, Slater says, "I do spend time practicing with her, but I try and slip in a few 'Mamas' every now and then, just to keep it balanced and make sure everybody's happy."

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Slater — who shares daughter Eliana and son Jaden Christopher, 21, with ex Ryan Haddon — says his new baby girl is "a wonderful spirit" who is also beginning to stand, which is "very exciting to see."

"It's really incredible. She's smiling all the time," the Mr. Robot actor raves. "It really does brighten up your life. She's a joy to be around."

Some of Slater's favorite activities with his little one include "blow(ing) her kisses," "toss(ing) her up in the air" and "tak(ing) her swimming," as well as their "ritual every morning" where he feeds her and then "take(s) her for a walk in a BABYBJÖRN."

"And then I got her this little swing that you just hook up, and that's great. She loves to go in the swing and seems to enjoy that and laugh about that. She loves books," Slater tells PEOPLE, sharing that one of his little girl's favorite stories is Hug Machine by Scott Campbell.

Slater is just as proud of his older daughter, who was "two days away from graduating high school" at the time of the interview and set to celebrate in part with a Zoom party — and with T-shirts her dad ordered that "say something like, 'Quarantine Graduate of 2020,' " he explains.

"[Eliana] has really blossomed as a very beautiful, intelligent, wonderful, very kind, lovely person. She's great with the baby and just a really warmhearted, special person," Slater praises his middle child.

"I'm proud of her and her being ready to take on life and have some of her own independent adventures now," the father of three adds.

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