Yeah ok mechanically it could be the lucky feat (lets you reroll three D20 rolls every long rest) or human determination which is a race characteristic that lets you pick one D20 roll every short/long rest to have advantage on. Human determination feels accurate for Simon's character I think!

The avocado scale is the humorous corollary to the avocado justice theory and that is another reason why I greatly appreciate it.

There's also a Los Campesinos! song that I like that is very moody and emo because that's their deal but the chorus does have the lines "A heart of stone, rind so tough it's crazy/That's why they call me the avocado, baby" and I can envision August singing that in a kind weird fever dream alternate canon. He would be into the emo vibes, maybe??? lol ok this is becoming goofier by the second now.