Sharing Mass effect DLCs on same console between two different profiles

When you originally bought the Mass Effect 2 dlc was it on this same console? If it was not then it wont work with your brothers profile

When you purchase content it is tied to the console it was purchased on as well as the console it was purchased on. That console license allows all profiles on a console to share the content. So yes, if you purchase something with Account #1, Account #2
will have access and vice versa.

There are a few pieces of DLC that can't be shared, but it's very few. And avatar content cannot be shared that way.

I liked the Mass Effect 3 ending, I have no idea why people hated it. I guess I could understand, I use a different profile for Mass Effect and have all the DLC, I'm playing Mass Effect 2 DLC, can't wait to check out 3's.

A license transfer is what you need to do. You can either follow the instructions here
http://www.xbox.com/drm or you can do the process on the console alone.

Sign in with the account which bought the content on your new 360, go to the MY Xbox channel and press A on the second square (the one with your Avatar).

On this new screen move once to the right and on this panel choose Manage Account.

Now scroll to the bottom and pick License Transfer. In a couple of button presses the licenses will now belong to your new console.

However now you need to refresh those licenses by setting the content to download again, you'll find your Download History on the same panel as the License Transfer.

Simply set that content to download again, don't worry about download time since if the content in already on your hard drive all that will eb grabbed will be the new license files.

Once all that is done you will hopefully find that the other accounts can once again use your content. Be aware though that the process is all or nothing, you can't pick individual items to transfer and enabling the games to be played by other profiles on your
console will stop that function on other 360s.

ddom -ps3 allows complete sharing game/dlc between two consoles -two profiles where only one profile purchased all content second profile uses it just as if purchased with no fees involved. First is ps3 plus but second profile gets to use content too. 360
will share on one console which is how I got MassEff 2 cerbious dlc with my profile even it was installed with son profile did the same with ME3 online pass. Publishers control alot but still relie the platforms .WE are in control with are bitiching and wallets.