At some point, you will want to upgrade a FurrSol as it increases their base attributes which translates to more FLUFF being produced. You can upgrade a single FurrSol up to 6 times with corresponding requirements. To upgrade a FurrSol, you will need some FLUFF and another FurrSol to devour. The increase in base attributes depend on the attributes of the FurrSol they are about to devour. See the table below to find out how the increase in attributes work.
You can only devour a FurrSol that with zero upgrades.

Upgrade Example

A player wants to upgrade his FurrSol for the first time. To do this, he will need 1000 FLUFF and another FurrSol to devour. Since this is the first upgrade, 5% of the attributes of the devoured FurrSol will be added up to the other. The devoured FurrSol will then be burned. And the upgraded FurrSol will have a higher set of base attributes. See image below.