Crotalus is a bubbly, spunky, happy-go-lucky gauntlet that may be bought at Ra'Virr's Tradehouse. She is sentient, and quite a personality. She has dedicated voice acting, an origin story quest, and a load of neat enchantments geared towards any player! Her price varies depending upon your Mercantile Skill and your Disposition with Ra'virr, but she is well into the quadruple digits. Unlike most companions, this one doesn't have to be taken care of (only repaired!).

She comes complete with: 

    ♦ A great enchantment, including a Strength Buff, Magicka Buff, Sanctuary, Spell Absorption, and Water Breathing. Her enchantments ensure that she is suitable for most characters.

    ♦ The ability to mend your gear while adventuring, at the modest cost of gold as a magical component. 

    ♦ 46 lines of voice acting, including 31 ambient dialogue lines and 15 unique dialogues for certain locations or events.

    ♦ 100+ lines of text dialogue, including several topics.

    ♦ The ability to reduce how often Crotalus speaks, or even to make her stop speaking ambiently entirely (In other words, you can turn off the voice acting feature of this mod, if you so choose. When this happens, Crotalus talks only when you talk to her).

    ♦ A single quest, one that involves finding her creator and in the process, coming to know herself.

    ♦ A PG (non-explicit) "sex scene" (We're talking fade to black here, WITHOUT voice acting). How does that even work?
Asset Creation: PikachunoTM. Note that this asset is unique to this mod, and can only be used after crediting PikachunoTM.

Voice Actor: An anonymous and very special, dear friend to me. 
Notes: 

When arriving at Vivec's Temple district, Crotalus will remark on the size of Vivec's Temple. However, without MGE XE or any other distant land generator, you can't actually see the temple from the place she normally mentions it. 

Don't mind the odd file names for the voice acted lines. The voice actor herself named them.
Bugs:

Sometimes, when going to a location in which Crotalus has a scripted unique voice-acted line, she may talk over herself, partaking in regular ambient dialogue at the same time as her scripted dialogue. This is very rare, and happened to me only once during testing due to the infrequency of ambient dialogues.

For some reason, sometimes a subtitle for one of Crotalus' lines may appear without her actually saying anything. This is very mysterious to me, and has only happened once.