I suggest you try kennen.
First of all he's ranged, so it's not easy for him to all-in you.
Kennen can choose to farm with his Q. Easy cs, good harass if necessary, not too resource heavy.
Kennen can max W for stronk harass
Kennen possess enough punch to be a threat on his own at 6. You could very possibly win at level 6 depending on HP level, passive stacks and if you can land your shuriken.
Kennen has good followup on ganks (darius is not that safe vs ganks, although he can win out 2v2 usually)
Kennen is good for solo queue and mid-late game. If you have zhonya's, he'd think twice before flash E you in team standoffs
Remember that darius wins so very hard if he ever gets a full combo engage on you. Champions like GP/Panth may do ok but no matter how good you are, theres a risk of darius getting a pull on you when you cs. Darius only needs 1 good trade to give himself like 3 waves of free farming (just because you walk away with 60% doesn't mean you can keep playing aggressive. pots take time, you can't run the risk of him blowing the combo+ignite + flash for another auto or two, not to mention ganks). That's why kennen is super safe and you should AT LEAST not lose lane to him and will always play an impacting role for your team
Hope that helps
P.S: oh if you're scared of pushing, you could just not auto him and instead thro shurikens. Spells don't pull aggro.