What pulls the electrons from iron in rust formation? In the first step of formation of rust in iron, there is something that pulls electrons from the iron lattice, resulting in the formation of $\ce{Fe^{2+}}$. The reaction is:

$\ce{Fe  -&gt; Fe^{2+} + 2e-}$

After that positive iron is repelled from the lattice, it is dissolved into water and a lot of reactions take place. 

What is the thing that pulls the electrons from iron? (I guess it must be something positive, right?)
The iron is being oxidized in this process. You just need something to act as an oxidizing agent. Dioxygen will do quite nicely:

$$\ce{O2 + 4e- -&gt; 2O^{2-}}$$