Living in the deepest parts of the ocean is difficult, especially when it comes to food. But being the madlad you are, you were able to survive. Now as a trophy for your efforts, you gain immunity to acid damage, and any damage done via poison, rotten food, raw food, or any other damage delt by consumption.

Due to being extremely long, your size class is large.

Due to your new, alluring, and strong nature, you have a  +2 in CHA, and a +1 in either CON or STR. However, being in the darker parts of the ocean floor ( maybe 3500 to 5000 ft below sea level ) You often reside in smaller caves and such that fit you, and don't have much room to stretch and such. You have a -1 in DEX.

Sea welling creatures often float by your people. This has created a sort of relationship, helping each other when greatly needed, due to the similarities in alignment. With this, you have the ability to communicate simple ideas with hostile and non-hostile creatures that can breathe water; although you have no ability to understand them in return.

 The evolution of your people has granted you sharp canine teeth (not unlike a shark) and extremely powerful jaws. When making an unarmed attack with your jaws it will deal 2d6 damage+STR or CON+Proficiency Bonus. You may choose STR OR CON, not both. If you replace one of your canines with a mineral, it will deal an extra d4 of damage.

Once every long rest, you may use this trait. Roll 1d8 to see how long this affect lasts. When in use, your bioluminescence is extraordinary, and to those unused to your extreme beauty, (no save required) you have advantage in CHA (intimidation) checks and CHA (persuasion) checks. However, when this is in affect, your dazzling scales may not be helpful when trying to hide. Gain disadvantage in stealth checks when this is in affect.

Due to your time in the darkest depths of the ocean, you have a Darkvision radius of 120 ft.( You already know what Darkvision is you can't discern color or something blah blah blah) And due to the waters of the undersea being so cold, you also have a resistance to cold damage.:)

 You have been deprived of the sun, surface food, surface landscapes, surface humanoids, surface monsters, and other miscellaneous surface things, you have no idea what you're doing- and have sense developed quirks. Roll a d6 or choose the quirk you must apply to yourself in the table below:

1. 

You have an extremely odd affinity with trees, ( This can be for any reason ) and often have the urge to climb them and spend time with them. Whenever you are in a forest or woods like environment, make a DC 18 WIS save. If failed, you climb the tree, however soon find yourself suck atop the large plant. You must find a safe way to get down, or take 6 falling damage. :)

2. 

Whenever you came to the surface, the first thing that caught your eye was the sun. Due to this strange ball in the sky, you often become interested and intrigued- then attempting to study it, ending ultimately in you staring at the sun. After each long rest,( if the sun is in view ) roll a d6 but replace the 6 with a 0. You then take said d6 radiant damage.

3.

Being used to having little to no hostile creatures in the deep parts of the undersea, when creatures are hostile to you or your party, you can't help but be slightly surprised. Whenever initiative is rolled, you are automatically surprised.

4.

Not having any alcoholic beverages in the undersea, if you happen to intake alcohol, you must succeed a DC 15 CON save, and if failed you take 5 points of damage ( this is not able to be resisted with the 'Extreme Metabolism' trait ) and if failed 3 times, or you roll a nat 1 on one of the saves, you fall in unconscious.

5. 

You are allergic to dogs, cats, birds, pigs, and horses. If you are within 5 feet of one of these animals, you take 1d8 damage. You cannot be allergic to animals that are part of a spell or ritual, and you are not allergic to animals that are undead, celestial, infernal, primordial, or otherwise.

6.

Unused to the pressure of the overseas, falling sleep is continuously difficult for you. When attempting to long rest, you must fail a DC 12 CON save, or suffer the affects of not taking a long rest.

Due to your interaction and nature of your people and they things you accosiate yourself with, being a good alignment is nearly impossible. On the lawful spectrum, the society is quite free, so this may range and vary from Triton to Triton.

( Tends towards any alignment other than good, and chaotic evil characters often have some sort of trauma to push them this far into power and chaos )

After being on the surface for some time, you are now able to enhance your bioluminescence to a point where it can be seen even on the surface. At level 3, you are able to cast dancing lights once per long rest. At level 5, you may cast this twice every long rest. For every level above, you may cast once every short rest, plus one per level. ( Level 6 once per short rest, level 7 twice per short rest, level 8 three times per short rest, etc.)