Lucy Letby once told a colleague about the death of a child in an "excited" and "gossipy" way, a inquiry has heard.
Giving evidence at the Thirlwall Inquiry, Melanie Taylor said she could not remember which baby's death Letby was referring to, but recalled how she spoke about it.
She said: "It was almost in a way that she was excited to tell me, almost in a gossipy manner."
The inquiry at Liverpool Town Hall is examining how the killer nurse was able to murder and attack babies at the neonatal unit at the Countess of Chester Hospital in 2015 and 2016.
Rachel Langdale KC, counsel to the inquiry, asked Ms Taylor if the way Letby spoke about the baby's death struck her as unusual or disrespectful.
Ms Taylor said: "Yes, it did. There were parts of [Letby's] personality that were a little strange to me, so I took that as a personality difference between me and her."
The inquiry continues.