So I was doing some digging in the files because I was curious about what that nest in Pentil Woods does, and found out about Sear.
Being bored with the virus and whatnot, I changed a little bit of Jaffee's dialogue in Pentil to reference Sear, and then activate the encounter when you next visit the nest.
I THINK he's overloaded on text, because I couldn't change much or even add a third text line without getting an error, but it could be my own error.
However, this does work in my own game. You don't get any quest rewards or special gear or anything, but hey, the nest does something now.
If this doesn't work for some reason, lemme know and I'll try to fix it. No promises though.
Just drop this right into your Scripts folder and that does it.
Fight Sear
Be sure to create a backup copy of your game before installing this script. This is to make sure you can restore the original version of your game should something go wrong!