I made two pieces where your little dude (Wren) meets my not-so-little dude (Docile)
It only took me around 2 hours and 53 minutes in total (surprising, but then again, I swapped styles for the second one and the first one is significantly more simple to do (I also, didn't have to draw Docile more than a small portion of their tail in the first one so-).)
Also, this is size accurate to when Wren is small. Docile is significantly bigger than Sebastian, and could accidentally crush poor Wren if they so much as twitched wrong.
For further lore/info: Docile relies a LOT on their sense of smell, and the scent that the cause of the shrinking carries was on a different expendable who committed the crime of hurting Painter and got the special STTS ending in which Docile gets to kill you (which is only in my au because they're an OC), and it only resets Painter because Old Man fears the Ancestors. Wren has traces of it and Docile nearly goes to murder him until they realize it's just a itty bitty expendable, not the evil, and gets absolutely fascinated by the tiny dude. Wren had also been trying to find somewhere to hide to patch himself up with his mini medkit in this scenario (since otherwise it wouldn't make sense).
HOLY— DOCILE IS HUMONGOUS I LOVE HIM
Man, Wren already freaks out over Seb being so big in comparison, and I've had this thought before if Wren ever came across the Guardian Angel while they were itty bitty. I don't even know if they could fathom it. Especially if their first encounter with it was when shrunk. An encounter with Docile gives me a similar vibe, except he's not chained up and can actually move around. Probably terrifying!
RIP to that one expendable that hurt Painter, I hope Docile finds them and gives 'em hell >:D
Thank you for drawing Wren! It's really fun seeing other's OC's interact with them 💕 I love the fixated sparkles in Docile's eyes, reminds me of when I find A Really Cool Moth ™
Sorry it took me a while to answer this one! Been busy and wanted to give a proper response to ya!