Like any big brother and sister, Harry and Molly Flynn know to look after their baby sister, Isobel.
But these brave siblings, aged 10 and seven respectively, have taken this to a whole new level by saving her life at least 100 times.
Born premature at 28 weeks, Isobel (3) has apnoea, which means that she stops breathing, with a particular tendency to do so when she is asleep or has had a shock.
Luckily the family from Waterford come from a long line of Red Cross volunteers and have been junior "T-Bears" since the age of five, with some Red Cross medical training - which means that they take it all in their stride.
Yesterday they attended a Red Cross Picnic for Principles event at Merrion Square in Dublin, celebrating the 50th anniversary of the Seven Fundamental Principles of the Red Cross and Red Crescent movement.
Mum Maria said Isobel was born weighing just two pounds and spent the first 10 weeks of her life in hospital.
She was just home a couple of weeks when the first frightening incident happened when she blacked out.
Harry, then aged seven, was holding his sister in his lap in the sitting room, with the rest of the family in the kitchen when Maria suddenly heard him saying: "Breathe, Isobel, breathe.
She rushed into the sitting room to find her son holding the baby's nose and giving her breaths.
"She was white and purple - he was holding what looked like a dead child," Maria recalled of the terrifying episode.
But soon after, Isobel took a deep breath and regained consciousness.
"Harry was very calm," said Maria, adding that, since then, he has gone on to save her life over 80 times so far.
Isobel's condition is far worse when she is sick or has a cold, revealed Maria, saying it could happen 20 times a day.
Harry himself told the Herald that he doesn't find it frightening when this happens.
"It's fine because I know what to do," he shrugged.
"My family are basically the leaders in the Red Cross in Waterford so I will always be a Red Cross volunteer," Harry vowed.
Meanwhile, Molly has also saved her sister's life over 20 times so far, with one of the most startling occasions happening just a few weeks ago while out grocery shopping.
Maria said that the two girls were in the trolley when suddenly Isobel keeled over in the supermarket and stopped breathing.
"Molly sprang into action and gave her six breaths by the time I had dropped the shopping and reached the trolley," said Maria.
The family hope Isobel will grow out of her apnoea by the time she is four.
But in the meantime, Maria said she has as normal a life as she could have thanks to her quick-thinking siblings who had the medical training she needs.
If there's one thing comedian PJ Gallagher is grateful for, it's that he didn't read midwife June Goulding's memoir, The Light in the Window, before he met his birth mother.