The is a popular theory that due to "Southern Ambitions", Rickard Stark betrothed Brandon to Catelyn and Lyanna to Robert, allying the North with the Riverlands and the Stormlands. That by having Ned and Robert fostered at the Eyrie, they were cementing a friendship thereby allying with the Vale.
Creating the STAB alliance; Stark, Tully, Arryn and Baratheon.
1. Was it created for benevolent or malicious reasons?
2. What were each of the lords thinking when they betrothed their children? What were their goals?