You wouldn't need Resilient CON because since you started fighter you have proficency in constitution saving throws. So maybe Resilient wisdom or an ASI for that level?
Kobold is the choice i would go with, you get booming blade as a racial feature plus the draconic cry gives you advantage for a bonus action and since we don't need the bonus action for the disengage that means 3 different ways to promt sneak attack. Definitely agree that you should go with fathomless warlock( if you aren't going straight rogue), i would drop fighter, start with rogue take a 1 lvl did in warlock go to subclass with rogue 3 more levels in warlock get your asi or feat plus your invocation than go rogue the rest of the way. If course i think this rogue is good enough on its own, especially if you take magic initiate with your first chance, with being a kobold you already get booming blade ,so grab Eldritch blast and either presdidgiation or mage and and hex and now you have a kit that is great at combat, and social encounters.
Grasp of Hadar is only once per turn. Repelling blast is the one thats every beam.
It's time!! Build!!! Build!!!! Build!!!!
Let's get it!
You wouldn't need Resilient CON because since you started fighter you have proficency in constitution saving throws. So maybe Resilient wisdom or an ASI for that level?
Chef feat!
Kobold is the choice i would go with, you get booming blade as a racial feature plus the draconic cry gives you advantage for a bonus action and since we don't need the bonus action for the disengage that means 3 different ways to promt sneak attack. Definitely agree that you should go with fathomless warlock( if you aren't going straight rogue), i would drop fighter, start with rogue take a 1 lvl did in warlock go to subclass with rogue 3 more levels in warlock get your asi or feat plus your invocation than go rogue the rest of the way. If course i think this rogue is good enough on its own, especially if you take magic initiate with your first chance, with being a kobold you already get booming blade ,so grab Eldritch blast and either presdidgiation or mage and and hex and now you have a kit that is great at combat, and social encounters.
At Lvl 10 its a rogue 4. Barely a rogue build. Sounds more like a warlock at that point