And although we still don't know the little boy’s name, Khloe posted a cute series of photos of older sister True carrying her brother dressed as a Tiger.
“Owlette and Tigger aka True and Baby Brother,” she captioned the post.
In another picture, Khloe zoomed in on his cute little pair of Nikes.
The cute snaps come after fans spotted Tristan attending the Halloween party thanks to a quick appearance in North West’s TikTok.
North, who shares an account with her mother Kim, shared a compilation video from the event and fans spotted Khloe, her two children and Tristan arriving together.
Khloe, who was dressed as a cat and Tristan who was holding an iron man helmet appeared to be a united front, despite the couple splitting over revelations Tristan was cheating yet again - this time while they were expecting their second child together.
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Tristan's surprising appearance wasn't the only eye-catching sight in North West’s TikTok - with many fans surprised by the nine-year-old's gory Halloween costume.
North showed herself dressed up in a frightening alien mask with blood pouring out of her mouth in the video.
The latest Kardashian Halloween party comes just weeks after Kourtney and Travis were called out for their own gruesome Halloween decorations, with fans calling them “unnecessary.”