If you can't connect to your subject get a lens with gimmicks, it will distract people long enough, if you can connect with your subjects, or want to learn, get a lens that does without them.
I've noticed that if you don't personally own the lens you're like a petulant child... you don't need it, gimmicks, you can use a cheaper lens. Sure you don't need them but if you have the means to buy the tools then do it and don't fear using them in any situation. As for the fish being being used as a gimmick and not being connected with your subject... that just shows your complete lack of familiarity with a lens you don't own. If you do own a fish then pull it out and try, you'll see it can be used quite effectively. You have to be quite connected with your subject to pull off these types of shots as you are right up in their face. I do agree the fish is a special lens but to never use it for portraits is as asinine as your statements regarding it.
I feel a bit nervous commenting here given all the experts.
I love the 85L, however my advice would be the reverse, use the 85L for Adults and 135L for kids.
The kids is not always gong to sit still while the 85L slowly AF's.
Having said that, they are both excellent lenses.
I think my point here is "rules" about the use of any lens for this application only or that one, or... is really doing no one any service. Any lens can be used in any situation; kids running, portraits, action, stills, etc. The only limit on their actual use in the real world are the limits you place on them yourself. I just choose not to limit myself...
Just to make a point about the fish and portraiture. I took this shot a few years ago while shooting strangers at the beach. Read my description of this shot. Part of the biggest aspects about taking portraits for the 100 Strangers project is connecting with people, pictures come second. I know this because I was the admin for this group for years. In order to take this photo I had to talk with this woman and explain why I needed to be right up in her personal space. She agreed, loved the results and actually hired me to do ads for her yoga studio later. She is still a client. That doesn't happen when you're not connected with your subject. Sure there is distortion and it's not safe. If that worries you so much that it hinders your creativity stick with Hurley, safe and follow.