i'm a data hoarder, it'll get worse with time but right now i don't have a thousand hard drives, i just collect some shit.
as far as asriel's concerned, it's just a lot of images. alright that's not true, there's a fair few things - PDFs and txt files, a couple zips, buncha shit. but it's /mainly/ images. if you're interested, i'm not gonna host this for you either, but there's plenty of opportunities to collect. grabber, pixivutil2 and gallery-dl to name a few, and this stuff applies to any character, not just asriel. if you're a really insane you can go get hydrus which is an absolute godsend. get scratching, goatspeed.