IL - Sirens  

Always thought EA's mermaids were too positive? The new mod from zero will allow you to open their dark side. After eating a new seaweed, your mermaid will be reborn into a siren, she will have a thirst scale (like vampires) and she will be able to lure victims, drink their blood and devour flesh!

Requires the XML Injector and Death Interactions 

I was going to add a bunch of stuff to this mod, but then I was "asked" to give a look at Expanded Mermaids and that covers a lot of stuff already, so I decided to add mine on top without making doubled interactions. After all, all I wanted was more cruel mermaids, so this mod here is compatible out of the box with Expanded Mermaids, more on this later...

Otherwise, the interaction on the PC will not show.

So, from the PC, you will be able to get the Siren Kelp:

Only mermaids can get and eat it. Eating the kelp will turn your mermaid into a Siren (a Siren eating the kelp will go back to be a regular Mermaid) with the thirst for blood motive:

It will also unlock new interactions the siren will be able to perform when in water to satisfy this need:

Lure for a Small Drink - will fill half thirst bar and unfill half energy bar from the victim

Lure for a Deep Drink - will almost fill the thirst bar, and almost unfill the energy bar of the victim

Lure to Devour - completely fills the bar, kills the victim...

I'm not sure it will work in swimming pools, but it will drop the energy bar the same.

When not in water, mermaids will be able to fill the thirst need with all the things vampires can use to do it, provided that they meet the skill requirements to order the packs etc...

NOTICE: the replacements for the plasma stuff will not work with other mods altering the same thing, for this reason, the included file also alters the amount of thirst vampires and sirens get from them, though not much... this is a mod I had for myself updated for the occasion. This part of the mod is in a separate package.

The option Siren's Regeneration will reset the Mermaid age while filling the victim age progression (not aging them up, though... because water) (MOVED - only for Sirens. Patch not required anymore)

Eating the Siren Kelp will remove the Kelpie and Sea Witch traits. 

Now, Expanded Mermaids seems to be outdated, I'll try to see if what doesn't work can be fixed and eventually post the fix in the comment section of the mod in the near future, unless someone else does it before, while waiting for the original author to come back to it.