Even humans start to act super weird when isolated even for a month or so and Rocky was alone in Blip-A for 50 years and then alone with an alien for a while. His behaviour should be unhinged.
Things Rocky does when he got back from Adrien that weirds out other Eridians:
He (subconsciously) picked a facet of his body as his "face" and turns it sometimes to orient towards people or objects he's paying a lot of attention to or concentrating on.
That thing I've seen Chinese people on social media discuss where they use their own characters to reproduce an English word phonetically, with the actual meaning being a fun sidepoint. Rocky reproducing his closest approximation of words without existing Eridian equivalents (relativity, caffeine, all the colours) that sound like gibberish or odd mashes of existing Eridian terms.
Making "random" components of structures transparent for no apparent reason (Grace can't be here, Grace will never be in this part of Erid, but if he were, he'd be able to see)
The Eridian word for "See" is probably something to do with detecting light. Rocky would use this odd, scientific phrase the way a human uses "Oh, I see!" to mean "Oh, I understand." Like someone saying "I've used a Geiger counter to verify the radioactivity of this abstract concept" when they mean, "I get it."
You need to be Silent when watching someone sleep because you could wake them up. A completely incomprehensible idea to Eridians.
You discovered it, you get to name it! No, actually you're Not allowed to call the new molecule "Low Friction, high thermal stability two-parts-carbon-to-four-parts-fluorine" try naming it after your pebble!
1, 2, 3, eyes on me! (Eyes being another phonetically assimilated word)
Odd, overly clear accent. To make sure the software translated his words properly, Rocky was probably taking special care to perfectly reproduce words in the exact same inflection every time, no slurring or mumbling his way through.
dailybridgerton
gummygunk
origamiaround
2087
