I'm a sub-optimal methylator (couple of inauspicious MTHFR SNPs in my genome).

I've been taking betaine (TMG) and lecithin (multiple forms, best source is egg yolks) as both provide methyl donors. I've also started taking creatine (less than what a bodybuilder would). We can produce this ourselves, but the process uses up methyl donors

A lack of methyl donors can interfere with homocysteine being converted to methionine (it cycles back and forth) leading to high homocysteine levels.

I also take methylated versions of B12, B6, and folate. (B6 is key to reducing homocysteine, and B6 doesn't work until it's been methylated, which - you guessed it - requires methyl donors.

Probably unrelated: there's good evidence that a choline deficiency can lead to fatty liver (hepatocytes need choline to make phospholipids). Lecithin has lots (phosphatidylcholine, a methyl donor — but it’s unclear whether methylation maters here).