If the skin stretches, so does the tattoo. Think about it like a drawing on a balloon. The ink gets stretched, so it “thins” and becomes deformed. Same goes the other way. By themselves tattoos fade out if not touched up every decade or so, so if it’s not too much stretch it will usually just need a slightly earlier touch up. If it stretches too much and especially if it deforms it will look truly awful.
Noteworthy: if it stretches and then the person looses weight to go back to then weight when they got the tattoo, not all the skin “destretches” back to the original position. Makes for some funny / awful tattoos.
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