BTN: $53.94 (107.9 bb)
SB: $47.18 (94.4 bb) No sample, but presumably fish.
BB: $90.26 (180.5 bb)
UTG: $82.02 (164 bb)
MP: $27.50 (55 bb)
Hero (CO): $50 (100 bb)
Preflop: Hero is CO with A♣ K♣
2 folds, Hero raises to $1.25, BTN folds, SB calls $1, BB folds
Flop: ($3) K♥ 7♦ 8♥ (2 players)
SB checks, Hero bets $1.50, SB calls $1.50
Turn: ($6) T♠ (2 players)
SB checks, Hero bets $4.75, SB raises to $13, Hero calls $8.25
River: ($32) Q♦ (2 players)
SB bets $31.43 and is all-in, Hero folds
Not really sure what to think here at all ...
1. Do we EVER fold OTT here ??
2. Do we EVER CALL OTR here ?
3. If he checks river, I think I'm going for the third VALUE barrel, right ? Or should just X-back ? And if he x/shoves, we fold ? ... but
4. On what holdings in general would you put Villain here this entire hand given how it played out ?
Please answer ALL questions. Thank you in advance! 
And as played, I wanted to fold OTT, cause as you said - a raise from a fish there looks pretty strong, and especially as I don't want to call a LOT of rivers ... I guess I was just kinda hoping that he slows down OTR ...