Flop Two Pair encounter resistance-How to proceed????

[pofigistka]

Party Poker - No Limit Hold'em Cash Game - $0.25/$0.50 Blinds - 5 Players - (LegoPoker Hand History Converter)

SB: $33.11
BB: $58.59
Hero (UTG): $50.00
CO: $27.53
BTN: $36.05

Reads: <font color="blue">Villain is a 41/5 (after 700 hands) type who is 4 tabling, despite playing too many hands pf, I have not seen him get out of line. His ag factor is 0.59 total, and 3.1 on the turn</font>

Preflop: Hero is dealt A[img]/images/graemlins/club.gif[/img] T[img]/images/graemlins/club.gif[/img] (5 Players)
<font color="red">Hero raises to $1.75</font>, 3 folds, BB calls $1.25

Flop: ($3.75) A[img]/images/graemlins/spade.gif[/img] K[img]/images/graemlins/heart.gif[/img] T[img]/images/graemlins/heart.gif[/img] (2 Players)
BB checks, <font color="red">Hero bets $3.75</font>, <font color="red">BB raises to $12.00</font>

Pot Size: $19.50

What should I be doing in this spot against this opponent?