I am going to try and speak from both sides of the fence. As the parent of 5 daughters, some of whom were in the same boat as your son, they did come home, have a snack, change, and then we stressed hw should be done before dinner. As they got older, the times morphed into before and after dinner. We found with 2 of the girls that pushing the issue met with the "wall !" After losing our patience a few too many times (my dh was an ELA teacher too ), we decided to back off. Consequences were determined with them, and what was completed they took full responsibility for. Yup, they lost out on some possible great grades, but we found that grades did end up making a difference to them. Hey, it wasn't easy at all, but working with them and not against seemed to help a lot.
Now, as the teacher - how many times I have had this discussion with parents!!! I have taught middle school for 34 yrs now, and though I am no expert - hey, i just told you about our kids -you ladies seem to be the parents that care, that inspire, that motivate...and many of the parents I have worked with did not have that same level of interest. They loved their kids, but sometimes, their children controlled them.
Christy, someone earlier suggested you "back-off" a little. It might work. May I ask, when your other son is working, does this son just crave your attention, simply because he wants some? You said he is totally capable, but do you think he just might want more because he sees his brother get it?
Not knowing your sons, I can only rely on my personal experiences at home and in the classroom. My students have so many varying levels, but they do want my attention when they see someone else get it. Some really feel insecure without it.
Our kids do challenge us, omg they do! It's great to seek other's experiences, but ultimately you know them best. This can really be an age thing - but many of us can attest that it does get easier! Caroline