the boys have a thought experiment over what it would be like if caleb's echo fucked essek (would it feel the same? would caleb get some secondhand pleasure from it??) that quickly evolves into the realization that the echo could cast polymorph into an ape and fuck essek for an entire hour before disappearing (assuming caleb holds concentration the whole time). obviously they have to experiment in this

+ essek is a size queen and becomes an absolute wreck from this
+ caleb starts off very clinical, asking essek questions about how it feels (to play up the experiment but it's 100% just playful teasing)
+ caleb joins in, either during the "experiment" or after the echo goes away

im okay with either cis or trans essek