More Loki Issues

Last night was another weird night in the Blanik household. Loki had been a little grumpy during the afternoon, but last night he was unbearable. I really thought we'd got over this, but last night it was too much so I ended up throwing him out of the living room. Poor Ross couldn't move without Loki starting to growl. He turns his head on one side away from Ross, hackles go up and his whole body is stiff to the tip of his tail. As far as I can see Ross does nothing wrong, honestly I'd admit it if he did, he just has to walk into the room or get up to change position and Loki is off on one. You can see Loki's uncomfortable, you can see he's tense and bothered .. but why and what do I do about it? Shouting at either really doesn't help, Ross doesn't care and Loki get's more worried and more "growly." But of course convincing other family members not to shout is borderline impossible and sometimes out of pure frustration I find myself doing the same. That's why I decided last night that I just didn't want the hassle and Loki had to go!
It must be so confusing for Ross, one minute Loki is playing chase with him, the next he's growling and tense. There is no doubt Ross has a much stronger character, but Loki wasn't brought up this way either. Mikey was a great example to him, he was fair and calm with him, but the older girls have always fussed over him too much, particularly Asha who continues to mother him. 
To be honest I'm at a loss as to what to do, I've never experienced this before with previous males. They have either bonded and got on, or they haven't! (God did Dexi hate Jay!) These two are fine on walks and generally fine during the day, but the tension from Loki some evenings in ridiculous and I can only think it stems from a weakness in his character. Up to about 4 months old Loki was a very nervous puppy, but I bombarded him with everything and he really has come on a treat ... but as I've said before, maybe just maybe that uncertain puppy is still in there, maybe he's not confident enough in his own skin and that's why now he's unable to cope with being the "older" male, especially as the younger one has such strength of character.
This morning everything seems back to normal, it's reasonably calm and quite, though there is usually an eruption of excitement around 10.30am which is our walking time .. I'd love to know what to do for the best for Loki .. and Ross. I'd really love some professional advice, this is a behaviour issue not training, I'm a dog trainer and it's very different kettle of fish!