There is a great counter for darius top

Blitzcrank.

Blitz is good for this role because his kit is basically made to be a full counter for Darius'.

His passive helps avoid some darius' passive bleed damage and can stop his ult reset along with making him less likely to kill you with it because it can grant a large shield which will absorb most of the damage. blitz's q maes darius' q weaker for 1v1. darius starts his q, blitz pulls him in, darius' q fires and only hits blitz with the handle. Blitz's w counters darius's w's slow. Blitz's e will help in allowing you to escape from Darius if you are pulled in. Finally blitz's ult is AOE with a passive. The passive will help cs from a distance and the active can wave clear like crazy. It also is a silence which can help stop darius's combo.

Early on you just play a little bit safer and allow arius to push the lane some. Usually sometime before 10 minutes darius will push a bit too far and you can easily pull him under tower, e, and make it an easy kill.

Pros:

• useful regardless of if behind or not
• waveclear
• can literally play all roles (full AP, full AD, full TANK)
• being under tower is more threatening than having equalized waves
• decent escape
• ranged ult passive
• short e and ult cooldowns
• a grab
• silence
• knock-up
• shield
• good in ganks

Cons:

• hard to push lane pre 6
• limited overall range
• ult's passive messes with last hitting
• most abilities are only single target.