The HTC Butterfly 2 is a phone forever trapped in a nightmarish puberty of HTC industrial design. It uses high-end specifications like a 1080p screen and a Snapdragon 801 processor, but its plastic body is a step below HTC's flagships. It's packing a 13 megapixel rear camera, not unlike the newer Desire Eye, but it's saddled with the secondary Duo camera from the HTC One M8 (which is probably gone for the M9). The Butterfly 2 has identity issues, folks, issues which won't be helped by flashing all kinds of custom ROMs and modifications. But now you can totally do that.
Team Win has released an official build of the custom TWRP recovery package for the Butterfly 2. HTC is generally pretty liberal with bootloader unlocks (at least on phones that stay away from AT&T and Verizon, which includes the Butterfly series), so installing it should be very easy for anyone who knows their way around fastboot commands. Once you've got that finished, you can flash custom ROMs, back up your software, and install all manner of mods.
The Butterfly 2 doesn't seem to have a very active aftermarket scene, but an official build of TWRP should make getting root permissions easier at the very least. Remember to backup your system whenever you try something new... and also remember that getting back to a stock build for an over-the-air update might not be easy once you've overwritten the stock recovery.