Possible Rough Green Snake/Eastern Garter Snake Hybrid Found While Herping? Pics

I already posted this on rfuk so I'll just link you there because I'm not sure how to add photos here.
https://www.reptileforums.co.uk/threads/possible-rough-green-snake-eastern-garter-snake-hybrid-found-while-herping-pics-included.1292537/
That is my post there I might be stupid, we'll see. What do you guys think?

Well this cute little guy is definitely not a rough green/garter hybrid. Green snakes and garters are not only completely different species, they're not even in the same genus. So that's definitely not possible. As for what he could be, it's hard to say because the picture is a bit blurry but it looks like he could be a pastel phase garter of some kind or grass snake. If the latter, he wouldn't be able to breed with your eastern garter at all because they are also of two different genus.

1. Elisabeth is correct.

2. Why did you initially post in a group based out of the United Kingdom?

Per your post in the UK group:
3. Easterns are the only garter native to [Maryland]...
That's not true, Commons are also native to Maryland.

4. You've had this snake for about a year and a half and he:
a) has barely grown at all, despite having eaten pinky heads, slugs, nightcrawlers, fish, tadpoles, and even insects with exoskeletons, i.e. crickets, a beetle, a dubia roach. In my experience the quickest way to beef up a garter is to provide it with adult amphibians, e.g. frogs, toads, salamanders. (Check your local laws before collecting from the wild.) I've definitely noted a correlation between their white, or partially white scat (presumably digested skeletal remnants) and mass growth. [I'm sure more garter breeders would note this as well, but unfortunately many believe that parasites in/on amphibians somehow, over the course of the last zillion years that garters have been ingesting amphibians + amphibian parasites, have now become detrimental and therefore do not offer amphibians.]

b) is still super (cage) aggressive.
You're doing something wrong. I'm not sure what it is but it's something.

5. He's infertile because you've tried breeding him to your eastern garter twice, observed the lock, but no result?
So, you're sure you've got a 1.1 pair there, i.e. 1 male (the garter in question, you know it's a male) + 1 female. And you're sure the infertile one is the male, not the female. She is a proven female? When did you observe the locks? I've observed locks when I take the females out of brumation and add them with the male that I want them to lock with. You did brumate the pair, right? You took the male out of the fridge or basement a few days before the female. Have you bred garters previously?

If you can get some better photos then upload them to this site:
https://www.inaturalist.org/observations?place_id=39&taxon_id=28339

You'll get a lot more answers, but I suggest you leave out the hybridization theory.

Just an eastern garter my friend

I think it looks like it could be this snake. Look at the pics on google images.
*Peninsula ribbon snake, Thamnophis sauritus sackenii, green phase, native from Florida*

I still think this forum needs an irc channel, thanks for letting us use yours. :)