This only happens when Caesar summons you after you irradiate Cottonwood Cove | Fallout New Vegas
Woweeeeeeeeeeeeeeeeeeeeee how to irradiate cottonwood cove here: https://youtu.be/-4TBRisM-D8
Woweeeeeeeeeeeeeeeeeeeeee how to irradiate cottonwood cove here: https://youtu.be/-4TBRisM-D8