Silverfish are a formidable opponent in Minecraft when in large numbers, but that's all they have going for them: numbers. Aside from a few lonely blocks in the Extreme Hills, most players won't encounter many silverfish, and if they do, they only take one or two hits to dispatch. Making them stronger would completely break them, making strongholds unnecessarily difficult, but perhaps they would be better enemies if they actually dropped something (anything, really) aside from experience, or had more behaviors than just disappearing into the floor.
- Like their real-life counterparts, silverfish could occasionally eat paper, string, banners, sugar, and books (non-enchanted) when they encounter those items, like how pandas go after bamboo items. As they live underground, this would be a minor annoyance at worst, and endearing at best.
- Maybe little munching noises while they eat. :)
- For mob drops, this can get a little weird, but I was thinking maybe they could drop paper and string, but also maybe gravel and sand. Since they burrow into blocks, it would make sense that they eat their way into them.
Endermites are even less interesting than silverfish. I kinda liked it when they were some also a byproduct of endermen teleporting, but now they're just kinda... There. And they don't really do much.
- Endermites could teleport randomly, like a player eating chorus fruit. This would make them slightly more unpredictable to fight, but maybe not as dangerous as endermen. It would also be kinda hilarious when they teleport into a dangerous area and die.
- Endermites would still despawn after 2 minutes, except when currently hostile toward the player or a mob. In other words, if an endermite is trying to fight something, it will not despawn until the fight "ends" The fight could end by the endermite teleporting far enough away from its opponent, its opponent moving far enough away, dying, leaving its view, or killing its target. I'm not actually sure if that exception isn't already a feature, the wiki is missing that information.
- Maybe get rid of the "trying to burrow into stone" behavior. It's useless and looks buggy. It would be interesting to have endermites burrow into various sands instead. Currently, they suffocate in soul sand, but it would be better if they just burrowed into it. On that note, I would advise against making them able to burrow into concrete powder, for the sake of builders and architects. I'd go bonkers if my builds became infested with bugs, please do not code them to burrow into concrete powder.
- Could have a very low chance of spawning in the Nether, like endermen, and spawning naturally in the End Islands.
- Endermen should become hostile to all endermites, regardless of whether they spawned from thrown pearls or not. How do they know which endermites were spawned from eggs or pearls?
- Might drop: chorus fruit to explain their erratic teleportation.
If I think of anything else I might add it, but for now I believe that's all.