Little Isaac Is The BEST Big Bro! See Pics Of The 'Teen Mom 2' Tot's Sweetest Older Sibling Moments

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Isaac giggles with glee while spending QT with mom Kailyn and lil' bro Lincoln.

Over the years, we've seen Kailyn Lowry-Marroquin's firstborn son, Isaac, grow into a sweet, sensitive and thoughtful toddler, and now that the "Teen Mom 2" cutie-pie is an older brother, he's becoming the perfect role model.

From the moment Isaac met Baby Lincoln, it was love at first sight. Whether he's playing with the four-month-old on the Gymini or snuggled up with him during a nap sesh, Isaac is always beaming with pride and showing off an adorable, protective nature.

Kailyn and Isaac's father, Jo, may have their co-parenting issues, but that hasn't lessened the attention they shower onto their son. Clearly, the exes are doing something VERY right.

To celebrate our favorite lil' big bro, let's take a look at some of the most aww-worthy older sibling pics Kail has posted online. Prepare to swoon!

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There's so much to play with, but Isaac still can't keep his attention off the baby.

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Goodnight Moon and Goodnight Baby Lincoln.

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Who needs cartoons when there's an adorable infant in the room?

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Kiss cam! Isaac sneaks in a smooch while Kail's hubby, Javi, smiles for the shot.

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Isaac is Mommy's Little Helper, even when it comes to bottle-feeding.

Photos: Kailyn Lowry-Marroquin's Instagram