Sometimes they are very serious and a bit difficult and are sensitive flowers.
I've interviewed her before, in 1996, when she was playing Beatrice in the Jacobean tragedy, The Changeling, at the now long-gone Watershed theatre.
The theme of that play was transformation and she was difficult to interview, as she then acknowledged, because she was so caught up in the character that she found it difficult to "step outside"; she apologised for appearing reticent.
Rima Te Wiata reticent! That is what you can really call good acting.
She's famously a nut; a funny sheila who does impersonations. She did a brilliant one, of a chain-smoking Helen Clark on the political satire TV show, McPhail and Gadsby: 1990, The Issues. She still does impersonations, at parties, mostly. Couldn't she do Helen, for me?
"Oh, no, no! I like Helen. I'm not doing Helen any more. I gave her a hard time in the 90s. I'm not doing it any more. She deserves some peace."
She has met her a few times since, but the first time they came face-to-face was at the gym where they were both on rowing machines and caught each other's eye. "And she said: 'You don't look like you do on the telly.' And I said: 'Neither do you.' And we both had a little smirk and that was the end of that." She had of course just done Helen - "You don't look like you do on the telly" - and she is still pitch-perfect.
She did do Raymond Hawthorne for me. She said: "He'll kill me." Oh, go on. I shouldn't have asked. It was terrifyingly accurate. She loomed, and took my face in her hands and shouted: "You'll mock your arse off one day!" Who else can she do? "I don't know!" She did me, nagging, shrilly: "Who else can you do? Who else can you do?"
She is about to "do" the voice of the carnivorous plant, Audrey II, in the Auckland Theatre Company's production of Little Shop of Horrors. Audrey II is a male role, so she is embracing it with extra relish. She did Audrey II and that was even more terrifying than Raymond. It is an awful plant.
"I can't really say it's awful! Because I'm playing it. It needs food! It's starving! It keeps growing and it keeps getting bigger and bigger and bigger until it is absolutely enormous. The bloody thing is absolutely huge." It's a very manipulative plant.
"It's an addiction." I was going to ask how one gets into character to play a carnivorous plant but she beat me to it: You give up fags and then go back to them and then give them up again ..." She said: "I understand addiction because of cigarettes and things. Well, not things, actually. Cigarettes, in the past. I don't have one for about three months and then ... It's just so difficult."
She's not so bonkers that she got addicted to worse things. (Although somebody in the ATC kitchen overheard this and snorted, loudly.)
She might well have, you might suppose, because being the only child of two famous and much adored parents could send anyone a bit mad.
She is, Beatrice notwithstanding, supposed to be a bit wild and wacky. But is she really? She has always worked very hard and she takes her work seriously, obviously. When I mentioned that previous interview she said that, oh, she probably cared about what people thought of her then, in a serious role. Now she's just having fun.
Also, she is supposed to be funny so "when I go normal people think I'm flat. And sometimes you just think: 'I wish I'd actually presented that flat side so that people won't complain when you're not giving out that level energy all the time'."
She famously once walked off stage, in a huge huff, when an audience member rustled a lolly bag. This was during a performance of a play called Woman Far Walking in which cell phones had previously gone off.
"I probably wouldn't have done it if it hadn't been about real-life incidents; it was about the Maori flu epidemic ... and it just felt that the tikanga was all up the chute." She might have looked a bit precious. "Don't care." Or bad-tempered. "Don't care."
She is, probably, old enough now that she shouldn't care. How old is she? "Too old! Ha, ha, ha." She's been not answering that question for a very long time. "Too old to take any s***." She says if you go around telling people how old you are they won't cast you in roles that are written for any other ages. It's a funny old business is the acting business.
I asked, just in a by the way sort of way, whether she'd like to do more political satire on the telly and, well, off she went.
"Love to, but they don't do that any more. They put on all the make-up and prosthetics and everything as if to say: 'You're not capable of doing this. We need to put all this stuff on your face because you're useless and this has nothing to do with your talent. We need you to be completely replaceable and ...' Oh, f*** them. I'm over it. I hate people like them."
Blimey. What people? "These people that put together shows. You know, there's a sort of anti-talent thing going on."
People were always going to look at her talent and measure it against her parents'. That must have been horrible but she says she got over it a long time ago.
Still, she will always be, obviously, the only child of a famous actor, her mum, Beryl; and her very famous singer father, Inia, who died when she was 8. Inia, the much adored and, if you believe what you read, (and when you do, it is by the way, SADLY, of now yellowing newspaper clippings, and her mother's biography which is also a love letter), saintly celebrity before celebrity was invented. You'd think it might have been tough, enough to make you all bonkers and weird growing up with an absent, adored (by her as well, of course) saintly father. Saying so caused rather a lot of paint to be stripped from the walls.
"I don't think he was saintly at all!" she said, and howled with laughter. Her mum is now 87 and is in a retirement home. She wasn't sure whether she wanted to tell me that she has progressive, age-related dementia but then she decided she would because "it's not actually as bad as people think, that condition. One of the great benefits is that she was an incredibly organised person ... She could organise anything in a flash and now she doesn't have to do all of that and she can't remember that she hasn't had to do all that. She's got a lot more tranquillity in her life. And she's still got gusto."
Perhaps gusto, like talent, can be in the genes. Perhaps kookiness can be too. Mother and daughter share a silly, giggly fascination with teeth and she doesn't have a clue why; they just find teeth hysterically funny. She wanted to be a dentist but she was too thick. I'm not saying she's thick; she often has; it's another role she likes to play. She might have been a bit thick at school. She got 3 per cent in School C maths. That's quite thick.
"It's really thick." She says she was too thick to understand that you had to concentrate at school and "I didn't even understand that if you didn't do this now, that if you didn't concentrate now, that was it."
Oh, she seems to have got on all right despite her now legendary thickness. Beryl didn't much mind. "I had a mother who was too thick to understand as well. She left school at 14. How the hell did she know? She used to say: 'Don't worry, dear. Just be nice to people and that's how you get on in life.' And she was bloody right too, actually."
She seems to take this being nice to extremes in her private life. She says she has a saviour complex, although she thinks many women "who are perceived as successful and who are quite easily manipulated" do. She shrieked some more when I asked if she had ever lived with anyone.
"Oh, quite a few! Don't make me sound like such a harridan that no one would approach me! Oh, God, no one will come and see the show. Thanks a lot! They'll be going: 'She's typecast as that awful plant!"' She has never married or been in a relationship which has lasted longer than about seven years. A shrink might say this has something to do with her father dying when she was young and her mother never marrying again, or even having a boyfriend and her growing up with the perfect love story to measure these things against. Who knows?
She might be a bit - how to put this? - energetic to live with, I would think, having spent a lively hour with her. She showed me the tattoo she got when she was 14. It looked like a blob to me but she said it was a rubbish bin with the lid open and a speech bubble saying: Rubbish!" She found this, like the teeth, hysterically funny at 14.
"Yes! And I still do." She likes silly things, like Spike Milligan.
She said: 'I get seized by being a bit mental. I'm irresponsibly spontaneous. You know, I probably don't have a level of sophistication, sometimes, that some women of my age have got."
And what age would that be? "Ha, ha, ha! What age would that be? Ha, ha, ha!" More paint fell from the walls. She had me pitch perfect, damn her.
So of course I'd like to say that she's as awful as that plant, but she's a delight: Funny, a bit barmy, not a bit thick, more than a bit stroppy. And who cares what age she is? Her legs still look great in a pair of fishnets.
Little Shop of Horrors is at Q Theatre from Nov 1-Dec 2.