I was soooo smug when L was born. Spouting off about how two kids was not that much harder than one, really. And it was true. Then. What's an extra newborn around the joint? Just bring 'em along and live your life. And have a build in excuse to sit down for a while because the baby needs to nurse you know. We already had all the infrastructure---the physical stuff, the routines, the child-care set up, the parental mind set. Going from 1 to 2 kids wasn't the same completely catastrophically life-changing experience that going from 0 to 1 child was. 1+1 was more like 1.5.
Until. L found forward motion and a pincer grasp and an iron will for whatever the hell he wanted to do. Now its not just meeting all the needs of two children: inputs, outputs, cleaning, maintenance, rest. There is this whole third entity of managing their interaction together.
When B was L's age, he could sometimes play around us, running, climbing, grabbing whatever he wanted. And it was fine. Cute & fun, even. We could either play with him, watch him from a seated position, or do our own thing. We cannot do this with L. Because L's #1 priority in life is to get whatever B has (and usually try to eat or otherwise destroy it). Puzzle pieces are thrown into the toilet, crayons are stuffed into mouths, books are torn. And B is not one to simply take it. The usual scenario is: B is playing nicely. L grabs B's toy. B runs after and hits or pushes L. L cries. L hits B. Repeat.
So we have to watch them constantly or keep them physically apart. This is harder than it seems because L wants to be around B constantly. If I separate them by floor, L will shake the safety gate on the stairs and yell. Separating them vertically used to help---I would set B up with puzzles, coloring, or books on the dining table. Recently L learned how to climb onto the chairs and straight onto the dining table. One of us has to physically restrain L when B is doing something not-L-friendly.
They do sometimes play together...throwing balls, pushing each other around on push toys, climbing onto and jumping off of tables (ummmm....wait....), wrestling, or simply chasing each other around. Note that all these activities are bound to result in one or both parties being injured in a maximum of 60 seconds.
Its practically impossible for one of us to handle the boys ourselves outside of the house unless they are contained in the stroller. I tried taking them to the park myself last weekend and it lasted about 15 minutes. B ran off onto the sidewalk (outside the park) and L found some trash to eat on the ground. I basically had to hold L while B ran around (imagine how much he howled), or have all 3 of us run together. I see people do it, and have concluded that either they are saintlier than I or (more likely) their children are better behaved.
I've heard that they will soon be "each others best friend" and play together. I am eagerly waiting that phase, because ya'll I am tired.