Allegations and rumors: "Sr Pascalina Lehnert (below) who was Pope Pius XII's housekeeper and secretary and faced rumours, apparently untrue, that she was his mistress. When Pius's ill-health declined dramatically in the mid 1950s Pascalina in effect isolated him from all but the most senior church figures, and was accused of taking key decisions in his name without consulting him, hence her nickname as the she-pope. She and Montini, who had been close to Pius, clashed strongly. His supporters believed she manipulated the failing pope into moving Montini out of Rome"

https://politics.ie/threads/allegations-involving-mcquaid.177243/page-13 

The she-pope, also called La Popessa or La Papessa, was a The she-pope, also called La Popessa or La Papessa, was a Bavarian nun by the name of Sr Pascalina Lehnert (below) who was Pope Pius XII's housekeeper and secretary and faced rumours, apparently untrue, that she was his mistress. When Pius's ill-health declined dramatically in the mid 1950s Pascalina in effect isolated him from all but the most senior church figures, and was accused of taking key decisions in his name without consulting him, hence her nickname as the she-pope. She and Montini, who had been close to Pius, clashed strongly. His supporters believed she manipulated the failing pope into moving Montini out of Rome, and denied him the red hat, which was presumed to be automatic and would go with being Archbishop of Milan.)

Pascalina became a hate figure in the Vatican, and among the pope's family who desperately tried to get her sacked. She had basically latched onto him when he was nuncio in Munich (image below) and she was a nun there. She ensured, or he ensured, that she was brought with him to every other posting, including being pope. By the 1930s there were widespread rumours that she was his mistress. He (then known as Cardinal Pacelli) asked Pope Pius XI to order an investigation to clear him of the rumours. The investigation duly did.

But the rumours persisted as to what hold Pascalina had over Pacelli - whether it was just a close friendship or whether they were lovers. By the 1950s she was such a powerful figure in the Vatican that even Pacelli's family could not get him to see sense and dismiss her, and he did whatever she asked, including exiling Montini and denying him the red hat. To give an idea of the significance of that - Montini was widely seen as papabile: in other words, as a likely candidate for pope. All he needed to be in the race was red hat. But that was denied to him. (Even then, some of his supporters cast votes for him, as a mere archbishop, in the 1958 conclave.), which was presumed to be automatic and would go with being Archbishop of Milan.)

Pascalina became a hate figure in the Vatican, and among the pope's family who desperately tried to get her sacked. She had basically latched onto him when he was nuncio in Munich (image below) and she was a nun there. She ensured, or he ensured, that she was brought with him to every other posting, including being pope. By the 1930s there were widespread rumours that she was his mistress. He (then known as Cardinal Pacelli) asked Pope Pius XI to order an investigation to clear him of the rumours. The investigation duly did.

But the rumours persisted as to what hold Pascalina had over Pacelli - whether it was just a close friendship or whether they were lovers. By the 1950s she was such a powerful figure in the Vatican that even Pacelli's family could not get him to see sense and dismiss her, and he did whatever she asked, including exiling Montini and denying him the red hat. To give an idea of the significance of that - Montini was widely seen as papabile: in other words, as a likely candidate for pope. All he needed to be in the race was red hat. But that was denied to him. (Even then, some of his supporters cast votes for him, as a mere archbishop, in the 1958 conclave.)